The Best Way to Cut An Onion Into Strips for Fajitas 

Onions are an essential ingredient in many Mexican dishes, and when it comes to making mouthwatering fajitas, they play a starring role. Whether you prefer the sweet taste of red onions, the pungent flavor of white onions, or the classic yellow onions, knowing how to cut them properly can elevate your fajita game to a whole new level. These step-by-step instructions will show you the best way to cut an onion for fajitas, ensuring that you get those perfect, thin slices every time.

I LOVE fajitas for easy, quick meals.  They’re perfect for those nights when you just don’t really have the time or energy to make a big production, but still want something substantial. Just throw your peppers and onions into a pan, add some protein, and toss it all into a tortilla. Easy and delicious. 

For a long time, I didn’t really know how to properly slice an onion - for fajitas, or any dish really. But once I learned this technique, it made fajita night so much easier and helped me get dinner on the table that much faster!  (Psst: You can use this method for slicing onions for all sorts of dishes, like these Chorizo and Red Pepper Tostadas, Grinder Sandwiches, or this Fall Harvest Pizza Recipe.)

In This Post

• What You'll Need:
• How to Cut An Onion For Fajitas
• Helpful Tips
• How To Cook Onions For Fajitas
• What Else Do I Need For The Perfect Fajita?
• Popular Fajita toppings
• Recipe
• Comments

What You'll Need:

• One large onion. You can choose any variety here, and I’ll talk more about how to pick the right type of onion for your dish below, but I like to use larger onions, or if you only have small onions to choose from, use a couple. Onions tend to cook down a lot when sautéing. I usually start off thinking I have more than I think I’ll need, but once they cook, the amount is just right for my family of four. 
• A very sharp knife. This is imperative, as you’ll want to be able to easily slice the onion into thin strips. A dull knife will make this very difficult so use the sharpest knife you have.
• Large cutting board. Give yourself some room here to make it easier. 

How to Cut An Onion For Fajitas

Cutting an onion into slices for fajitas couldn’t be easier and takes just a few steps.  Here’s how to do it.

Step 1: Choose the Right Onion

The first step in creating the perfect fajita is selecting the right kind of onion. While you can use different types of onions like red, yellow, or white, each will bring its distinct flavors to the dish. Red onions are known for their milder flavor and vibrant color, while yellow onions offer a natural sweetness that can pair well with spicier peppers. White onions have a more pungent flavor that can add intensity to your fajitas. 

Ultimately, the choice of onion comes down to personal preference, so feel free to use your favorite. (Personally, I usually like sweet onions for chicken fajitas and red onions for steak fajitas. But the best onion for you will depend on the type of fajita you're making.)

Step 2: Gather Your Tools

Before you start slicing your raw onion, make sure you have the right tools on hand. You'll need a very sharp knife and a large cutting board. A sharp blade is essential for clean cuts and preventing onion tears.

Step 3: Prepare the Onion

Begin by cutting off both ends of the onion and discarding them. This will create a flat surface at both the top (stem end) and bottom (root end) of the onion, making it more stable and easier to work with. 

Step 4: Cut the Onion in Half And Peel The Outer Layer

Once both ends are removed, cut the onion in half vertically, following the natural lines of the onion. You'll now have two halves with flat sides. Gently remove the outermost peel of the onion (the papery part) and discard. 

Step 5: Begin Slicing

Place one half of the onion, the cut side, down onto the cutting board. Start by making thin vertical slices at an angle using radial cuts, starting at one end and working your way towards the middle of the onion. The angle helps create long, thin strips of onion, perfect for fajitas. Be sure to keep your fingers tucked in to avoid any accidents.

Step 6: Turn and Continue Slicing

After you've sliced one side, turn the onion around, keeping the flat side down. Start slicing again from the opposite end, at the same angle, until you reach the center of the onion. This method creates uniform onion strips that will cook evenly in your fajitas.

Step 7: Repeat for the Other Half Of The Onion

Repeat the slicing process for the other half of the onion. You'll now have a pile of beautifully sliced onion strips ready to be used in your fajita recipe.

Step 8: Store Any Leftovers

If you don't plan to use all of your onion slices immediately, you can store them in an airtight container. Be sure to keep them in the refrigerator to maintain their freshness.

Helpful Tips

• Watch your fingers! You'll be using your hands to hold the onion layers together while cutting so be very careful with that sharp knife. 
• Soften the flavor. While sautéing will generally soften the intense flavor of a strong, bitter onion, you can also soak them in cold water for a few minutes to give them a more mellow taste.

How To Cook Onions For Fajitas

There are lots of different ways to prepare fajitas! Here are my two favorite ways:

• On the stovetop. Place the cut onions and peppers in a large skillet and saute them in a little bit of oil over medium-high heat until soft and tender.
• Sheet pan fajitas. This is maybe the easiest way. Toss everything - the fajita vegetables, cut peppers and cut onions onto a sheet pan and cook until the protein has completely cooked through and the veggies are soft. Then serve with warm tortillas!

What Else Do I Need For The Perfect Fajita?

• Fajita Veggies. Consider adding bell peppers, either sliced or in thin strips, to your fajitas for added flavor and color.
• Protein. While traditional fajitas often use skirt steak or chicken breasts, you can also make delicious fajitas with ground beef, shrimp, or even a combination of your favorite proteins. At our house, we love chicken fajitas or steak fajitas, but have also been known to use tofu, fish, or even tempeh as a protein. 
• Homemade Fajita Seasoning. I often will use a store-bought fajita seasoning, but creating your own is super simple too. Create a homemade fajita seasoning blend using ingredients like chili powder, lime juice, and olive oil to marinate your protein and vegetables for extra flavor.
• Toppings. Don't forget to add your favorite toppings like sour cream, fresh salsas, avocado slices, and grated cheese.
• Tortillas. Serve your fajitas with warm flour tortillas or corn tortillas, depending on your preference.
• Sides. Don't forget about the sides! Refried beans, black beans, and Mexican rice are delicious alongside fajitas.

Popular Fajita toppings

Of course the onions, protein and peppers are the stars of the show when it comes to fajitas, but don't forget about the toppings! Use these ideas to amp up your dish:

• Sour cream
• Fresh Salsa
• Avocado slices
• Avocado crema
• Grated Cheese
• Jalapenos
• Cilantro
• Tomatoes
• Lettuce
• Lime Juice
• Salsa
• Mexican Coleslaw
• Chipotle Corn Salsa
• Guacamole

I hope this guide has shown you the easy way to slice an onion for fajitas. Following this method produces perfectly sliced onion strips every time. If you do use this guide, let me know what you think in the comments below! And don't forget to share a pic of the finished creation with me @frontrangefed on Instagram - I love to see your creations!  

Recipe