How Do I Keep Taco Shells From Closing Up In the Oven?

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If you use crunchy corn taco shells, such as Old El Paso or Ortega to make tacos at home, the instructions will tell you to heat them in the oven for around five minutes. This is done to crisp and freshen them up. So, you lay them on a baking sheet, heat them, and to your dismay, you pull them out five minutes later and the shells have closed up so that you can’t get the filling inside! Surprisingly, I’ve read all sorts of strange and precious rules on how to heat up taco shells. Taco shells are not an ancient culinary tradition with hundreds of years of attached lore. They are a strictly American thing. It doesn’t matter how you heat them! But it does matter if they close up and you can’t really use them.

🌮 Quick Fix: How to Keep Shells Open

If you’re in a hurry, here is the most effective way to stop taco shells from snapping shut in the oven:

The Overlap Method: Do not lay shells flat or upside down. Instead, nestle them slightly inside one another (like they are in the box) across your baking sheet. Each shell acts as a “prop” for the next one.

The Foil Hack: For the very last shell in the row (which has no neighbor to lean on), roll a small ball of aluminum foil and place it inside the opening to hold the shape.

Avoid “Face Down”: Never place the shells opening-side down on the pan; gravity and heat will almost always cause the sides to collapse inward.

Common Mistakes: What Doesn’t Work to Keep Cruncy Taco Shells From Closing

There is a lot of “taco lore” online suggesting ways to keep shells open, but most of them either fail or are unnecessarily difficult. Here is why the most common advice often misses the mark:

Laying Shells Face Down: It seems logical to stand them on their edges, but gravity and oven heat actually work against you here. As the corn oil warms up, the sides often collapse inward, leaving you with a “closed” shell.
Hanging Shells on Oven Racks: You’ll often see photos of tortillas draped over the metal rungs. This works for making soft tortillas crispy, but it won’t help a pre-formed hard shell. Plus, it’s a great way to get a burn or end up with a mess if your racks aren’t spotless.
Individual Foil Inserts: Some guides suggest wadding up a ball of foil for every single shell. While this works, it’s a waste of time and foil. You only need to support the “end” of the row; the other shells can support each other.
Eating Soft Tortillas: Taco pedants will tell you that real Mexicans only eat soft tortillas. Unfortunately, this also not keep your crunchy shells from closing in the oven.
Praying to the Taco Gods: They will not hear you, as they find crispy taco shells to be sacrilege. Hoping for the best will result in closed taco shells pretty much 100% of the time. Without intervention, heat and physics will snap the shells shut.

The Overlap Method: How to Keep Hard Taco Shells from Closing

The solution is simple. When you get the taco shells out of the box, you will find that they are placed one inside the other, in an overlapping fashion, to save room (and to make the whole thing more resilient and less prone to breakage).

Well, that is the way you need to bake them. Place each taco slightly inside the other on a baking sheet, but not to the extent that they are jammed together in the box. Each taco shell will keep its neighbor from closing up while heating. Then you just have one, poor, unfortunate taco shell on the open end which doesn’t have another shell to help it stay in shape. For that guy, you just need a ball of aluminum foil, about the size of a small lemon or a little larger. Stuff the balled-up aluminum foil into the open end of the taco shell to keep it open.

You do NOT need to place a ball of aluminum foil in each and every taco shell. Whoever is spreading this recommendation must be on the old tin foil board. Just overlapping the taco shells within each other will keep the adjacent shells from collapsing. Then only the last shell will need help in the form of an aluminum foil ball.

Pro-Tip for Storage: If you don’t use the whole box, don’t just fold the plastic bag. Use a heavy-duty freezer bag and squeeze all the air out, or better yet, a vacuum-sealed container. Corn is highly “hygroscopic,” meaning it will pull moisture right out of the air if given the chance!

You could also use a crispy taco shell rack, as discussed below. But, unless you are planning on baking soft corn tortillas in the oven to make them crispy, there is no need to buy one of these.

Problem solved. All the taco shells will stay open. You can save the ball of aluminum foil and use it again and again if you make a lot of crispy tacos.

Can You Eat Taco Shells Without Heating Them First?

You don’t have to bake crispy taco shells in the oven. They are ready to eat and perfectly safe to eat without heating. The reason we are instructed to heat them in the oven is to freshen them up. This provides a texture reset which will return the texture to a nice crispy state, and improve the flavor. .improve the flavor. But to understand why this ‘reset’ is necessary, we have to look at the physics of how corn tortillas react to heat.”

The Science: How to Freshen Taco Shells (And Why They Close Up)

To understand how to keep them open, we have to look at why they close in the first place. It comes down to two factors: moisture migration and starch retrogradation.

Moisture Migration: Even though they feel “hard,” taco shells contain a tiny amount of moisture. In the dry heat of the oven, the edges of the shell lose moisture faster than the “hinge” at the bottom. This uneven drying creates tension, causing the sides to pull inward—much like a leaf curling as it dries.
Starch Retrogradation (Staling): When corn tortillas are fried into shells, the starches gelatinize. Over time, those starches begin to realign into a rigid structure (staling). This makes the shell brittle.
The “Reset” Button: When you heat the shell to about 300°F (150°C), you are essentially “re-gelatinizing” those starches and drawing deep-seated moisture to the surface. This makes the shell momentarily flexible before it crisps back up. If there isn’t something physical (like another shell) holding it open during this flexible window, gravity and steam-release will cause the shell to collapse.
Flavor and Texture “Freshening”: While the oven resets the starch, it also serves to “wake up” the corn oils in the shell. Heating releases trapped aromas and evaporates any surface moisture that has been absorbed during storage, transforming a “cardboard” taste back into a toasted, nutty corn flavor.

🌮 The “Julio Fuentes” Problem

In an old episode of Sanford and Son, Fred Sanford was convinced his neighbor Julio had a secret “ethnic” trick for eating hard tacos without them shattering.

The truth? There is no secret. In fact, most of the world doesn’t even use these rigid, pre-formed shells! If you’re tired of your dinner falling apart, check out the reality of the “Taco Shatter” and why the secret might be simpler than you think.

👉 Read: Why There Is No “Magic Way” To Eat a Hard Taco

The Bread Connection: Staling vs. Molding

I often tell people that the refrigerator is a “double-edged sword” for baked goods. It’s the perfect example of the difference between a taco shell (or bread) being stale versus being inedible.

The Fridge Myth: You’ll often hear that you should never put bread in the fridge because it makes it go stale. While it’s true that cold temperatures speed up starch retrogradation (the process that makes bread firm and taco shells brittle), the fridge still serves a vital purpose: it stops mold.
The Trade-off: I’d rather have a stale taco shell that I can “fix” with heat than a soft one covered in green mold. Staling is a physical change in the starch structure; molding is a biological one that makes the food dangerous.
The Heat “Reset”: Just like you can save bread stored in the fridge by toasting it, heating your taco shells to 300°F (150° C) essentially “melts” those starch crystals.

By putting them in the oven, you aren’t just warming them up; you are physically reversing the staling process to make them crunchy and flexible again.

The Three Stages of a Taco Shell

Understanding the texture of your shell helps you know when to save it and when to toss it:

Fresh (The Goal): Light, airy, and snaps with a clean break.
Chewy (The “Damp” Stage): This happens when the shell absorbs humidity or the starches begin to lock up. It bends before it breaks and feels “leathery.” This is reversible!
Hard Stale (The “Rock” Stage): The starches have fully crystallized and the oils may begin to smell “off.” While heat can soften them, they will never regain that light, airy crunch.

Pro-Tip: If your shells feel chewy straight out of the box, don’t worry. Following the oven instructions below will “reset” those starches and evaporate that surface moisture, bringing them back to Stage 1.

Now, you know, in Mexico, they don’t use crunchy corn tortillas. They eat them soft. You should try that! You can make your own, of course, which takes some work. Or you could buy some from a store. It would be especially nice if you were able to get them from an authentic Mexican or Latino market. Warm up the corn tortillas by toasting them briefly in a dry skillet and use them like you would use soft flour tortillas. The “fresh” corn tortillas you can buy at the supermarket, unfortunately, have the texture of cardboard, for the most part.

Make Your Own Crunchy Taco Shells

If you’re into frying, you can make your own “crispy” taco shells by dipping fresh corn tortillas into boiling oil, at around 375°F. When using a deep frying method, you can use two pairs of tongs to hold the tortilla into a shell shape and then simply hold the whole thing under the oil for half a minute or so, while it crisps up (yes, it’s fast). You can also do this in a shallow pan with about an inch of vegetable oil.

Heat the oil until up to frying temp. Have a pair of tongs handy and place a corn tortilla into the oil, laying flat. Let it fry for 10 to 15 seconds and then use the tongs to lift one edge of the tortilla and fold it over into the shell shape you need. Allow the half that is still in the oil to fry for another 15 seconds or so. Then, flip the whole thing over and let the other half fry for 15 seconds.

Now, you have your crunchy shell. The problem is you can only do one at a time, but the great thing about this is that you can control how crisp your crispy fried tortillas are. So, if you want them a bit more chewy and flexible, you can do that. The other good thing is this will make those supermarket-brand corn tortillas worth buying.

You can also make crispy corn taco shells in the oven. But for this, you need a specialized piece of equipment, a crispy taco shell rack.

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Oven Method for Making Crispy Corn Tortillas

You can use an oven to make crispy taco shells, as well. Heat the oven to 375°F and use a tortilla rack like the one above.

To do this, you need to make your corn tortillas more soft and flexible. Most of these racks make 4 shells at a time, so place 4 tortillas between damp paper towels and heat them in the microwave for around 15 seconds. Then, spray both sides of the tortillas with cooking spray, or brush them lightly with oil. Place them inside the V shapes of the rack, so that they form shell shapes.

Bake them until crisp, about 8 to 10 minutes. This method is not foolproof because different tortillas tend to perform differently. You may have to experiment to get the desired results. As long as your taco shell rack has rounded tops, you can also try draping the tortillas over the top of the shapes and bake them in that position so that they retain the proper shape.

Some people have been known to drape tortillas over the rungs of an oven rack to make shells (2 rungs at a time). This makes a very wide shell with a flattish bottom, which may not be exactly what we’re looking for. It’s also a good way to get burned. And, to be honest, my oven is never that clean! Readers often ask how can I eat a cruncy taco without it falling apart? You may not like the answer!