Is it taco Tuesday or fajita Friday? There are a few key ingredients to these Tex-Mex dishes including peppers, meat, and of course, onions. As a result, it’s important that you prepare your ingredients properly. Believe it or not, the way you slice your onions greatly impacts their cook time, flavor, and ratio in the fajita dish. Let’s go over how to cut fajita onions perfectly step by step so that you’re always ready for fajita Fridays.

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What Kind of Onion Should You Use for Fajitas?

fajita onions

There are actually more than 13 different kinds of onions, so this is not a crazy question. Most fajita recipes call for white onion. The reason for this is because it has a much stronger flavor than most light onions. White onions are very zesty and sharp as compared to sweeter, yellow onions, for example.

However, a good back up option would be red onion. This is a kind of onion that is used in a lot of Mexican recipes like guacamole and has a strong bite to it as well. This is key because you will sauté your onions with some peppers before adding to the fajitas, so you want their flavor to hold up after being cooked to perfection.

How to Cut Fajita Onions?

When it comes to chopping up onions, there are many different methods like dicing, but fajitas are known for their long strips of onion slices. The onions are sautéd for long enough that they lose most of their bite, which means that you don’t have to make the pieces smaller as you do in a dice, for example.

In fact, fajita recipes use onions as a vegetable that you want to chew and enjoy whereas in other recipes, onions are usually hidden to add a certain flavor. We want to learn how to cut fajita onions to create a nice thick texture that we can see and taste clearly in our final product. Follow these steps to achieve the perfect fajita onion cut.

Step 1: Peel the skin off of your onion.

Step 2: Slice off the root and stem ends. Hold your onion sturdy with one flat side now resting on the cutting board. Cut the rest of the whole onion in half.

Step 3: Lay both halves of the onion flat on the cutting board with the long side facing upwards.

Step 4: Slowly begin to make vertical cuts that create slices about 1/4 inch thick. Once the onion gets to its core where it is the most tall off of the cutting board, turn it on its other side and continue this slicing pattern vertically.

Step 5: Put your knife to the side and pull apart each fajita onion slice to make sure they are all evenly cut into strips.

Extra Tips for Cutting Fajita Onions

  • If you recently cleaned your cutting board, dry it as thoroughly as possible
  • Wet a damp cloth (or paper towel) and ring it out. Then, place it flat underneath your cutting board.
  • Use a really sharp chef’s knife to cut your onions
  • Try a finger guard when you’re first learning to chop

One of the best hacks I have ever been taught is how to prepare your cutting board for chopping and dicing. Not only do these tips help your efficiency, but they keep the cutting process safe so that you don’t have to worry.

The wet cloth or paper towel will actually prevent your cutting board from slipping if you place it on top of another smooth surface. We don’t want the onions to get wet, so that’s why it’s important to dry the top and keep the wet rag on the bottom for stability.

The sharper the knife, the safer the chop. This is particularly true of fajita onions because we want them to be sliced easily into thick strips without hurting your fingers. I personally use the Cuisinart Chef’s Knife, which I will link below as a safe, sharp, and affordable option that is perfect when learning how to cut fajita onions.

How Should You Sauté Fajita Onions?


In order to get the onions nice and soft, but retaining their full flavor, you should sauté them for about 7-10 minutes on medium-low heat. All you need to add to the onions is some neutral oil, sliced bell peppers, and select fajita seasonings. These include salt, paprika, cumin, garlic powder, and chili powder if you like spice. Depending on how many fajita onions you want per serving, you can add anywhere from 1/2 teaspoon to 1 teaspoon of these seasonings.

This will not only flavor your onions and bell peppers, but it will give the translucent white fajita onions a nice sear. Once you add those onions and peppers to a tortilla, you will immediately taste the fajita heat and tang that pairs so nicely with the meat of your choice.

Now that you know how to cut fajita onions, which onions to buy, and how to sauté them perfectly, you are guaranteed to end up with delicious fajitas for dinner. The best thing you can do when it comes to learning how to perform different kinds of chops is practice. Cutting onions is a more challenging step of cooking than people think and can often separate good dishes from great dishes. So, keep trying until you get the perfect fajita cut.