If you’ve ever wondered how to cut onions for fajitas, It’s simpler than it looks and takes roughly 5 minutes to cut a whole onion.

Here are quick and easy steps to get you the best fajita recipe.

All you need is a sharp knife (we don’t want to cry over sliced onions), a large red onion, and a large, stable wooden cutting board.

Don’t worry. Cutting onions for fajitas is a breeze. There’s no wrong way to do it, just a few simple steps and two key tips I highlight below.

Original Post: 9/19/2023

Overhead shot of onions cut for fajita veggies

The Basics: What are Fajitas?

Fajitas are a versatile staple in Mexican cuisine. And if you’re a fan of Chipotle, you probably know how they can elevate your bowl, burrito, or quesadilla!

Fajitas are a mix of cooked onions and peppers that give your food a delicious sweetness.

This sweetness comes from the lightly caramelized onions and peppers, which release sugars and give them a beautiful brown color and a slight crunch.

Overhead shot of fajita veggies on a white plate

What Kind of Onions Should You Cut for Fajitas?

The best onions for fajitas are typically red onions because they don’t soften as much and keep their texture as they cook. They also give fajitas a nice pop of color!

But if you love sweet onions, they are great for caramelizing and adding an extra pop of sweetness.

Other really good onions are white onions and yellow onions.

There is no right onion for fajitas. All onions have a high natural sugar content and will all caramelize beautifully.

You Can Make Fajitas Without Onions (If You’re Not a Fan) For A Vegetarian Fajita

You can make homemade fajita veggies without onions, especially if you do not like onions. Substitute the onions with a different sweet veggie or use a rainbow selection of bell peppers.

I love combining a variety of colors, including green, red, and orange bell peppers, for a beautiful fajita bell pepper rainbow.

Also, you can quickly saute carrots or other colorful vegetables instead of onions. Carrots are great because they have natural sugars and caramelize beautifully.

The Best Way To Cut Onions For Fajitas

The best way to cut onions for fajita onions is a radial cut.

What Is A Radial Cut?

A radial cut means making vertical cuts instead of horizontal slices. Cutting slices from the outer layer to the center of the onion at a slight angle from right to left.

I added a diagram below to show the best way to make this cut.

Why Is The Radial Cut The Best For Fajitas?

The benefit of a radial cut is that it allows you to control the width and length of the sliced onion, which naturally becomes slightly thicker when cut in this direction.

Thinner slices tend to lose their shape.

Guide explaining How To Cut Onions For Fajitas with a pairing knife

The benefit of a radial cut is that it gives you control over the width and length of the sliced onion.

How To Cut Onions For Delicious Fajitas – Step-by-Step Guide

Step 1

Remove the dry outer layers.

Then, cut the onion in half through the root to keep the layers together. The key here is to keep the root end of the onion because it will help you keep the layers together.

Tip! Make sure the paring knife or chef knife is sharp.

A guide with the image of an onion identifying the stem and the root

A guide demonstrating the ideal way to cut an onion in half making sure to cut through the middle of the root to keep the onion layers together

Step 2

Carefully hold the onion on one side, with fingertips down on the onion as you slice the onion.

Make radial cuts while slicing the onion.

Make the width of the slices roughly 1/4 of an inch thick. Remember that the onion slices will lose water and overall thickness when you cook the fajitas.

Side shot of Radial cuts how to cut onions for fajitas

Step 3

Once you’ve made all the cuts, release the ones still attached to the stem by cutting them off of the stem of the onion.

overhead shot of onions for fajitas on a cutting board

Top Tips

Make sure your knife is extra sharp

It’s easier to slice an onion with an extra sharp knife that won’t crush it and release tear-causing chemicals.

Use A Sturdy Cutting Board

A thick wooden cutting board is sturdy and makes it easier to slice the onion.

I learned a useful trick in culinary school that I want to share with you. If your cutting board keeps slipping on the surface, take a piece of paper towel, moisten it slightly with water, remove any excess water, fold it in half, and place it underneath the board.

This will help keep your cutting board stable and prevent it from sliding around while you’re using it.

See Below for Detailed Instructions

The Right Equipment For This Recipe

1 Wooden Cutting Board
1 Chef or Paring Knife (Sharp)

Now, once you’ve cut the onions, all you have left are the bell peppers for the perfect fajitas.

Recipes For These Perfectly Sliced Onions

With these sliced onions, you can include all types of fajita fillings, including chicken breasts and grilled meat like skirt steak for steak fajitas. Try this delicious carnitas fajitas recipe in the oven.

Try pairing these with this Chipotle pollo asado recipe, delicious chicken fajitas on a bed of lime cilantro rice for the best burrito bowls.

Cook the fajita vegetables in a cast iron skillet, and add them to this pollo asado quesadillas rellenas (Chipotle Copycat) recipe.

Also, make veggie tortillas on corn tortillas and vegetable fajitas.

Side shot of Chipotle pollo asado recipe

Storage

If you have leftover raw onions, store them in an airtight container, ideally for up to a day.

When You’re Ready To Cook The Onions

Once ready to make fajitas, you only need a teaspoon of avocado oil to cook the onions.