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.)
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.
- 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
- Lime Juice
- Mexican Coleslaw
- Chipotle Corn Salsa
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!
How To Cut An Onion For Fajitas: Step By Step Method
- 1 large onion (yellow, red or white)
- 1 very sharp knife
- 1 large cutting board
- Using a very sharp knife, cut off both ends of onions and discard.
- Cut the onion in half, lengthwise, following the vertical lines of the onion. Peel the outermost layer of skin (the papery part) and discard.
- Place the flat end of one half of the onion (the cut side of the onion) face down onto the cutting board.
- Slice the onion at an angle, starting at one end, all the way to the middle portion and set sliced pieces aside.
- Turn the onion around, and starting at the opposite end, slice it again at an angle, until you reach the center of the onion.
- Repeat the slicing technique for the other half of the onion and use the slices for fajitas or other dishes that call for long strips of onion.
- Watch your fingers when slicing the onion to ensure you don't accidentally cut yourself!
- Store leftover onions in an airtight container in the refridgerator.
- To soften the flavor of a bitter, strong onion, soak the slices in cold water for 5-10 minutes before using.
- Serve with fajitas, tostadas, or enchiladas or other Mexican dishes.