For fajitas, cut bell peppers and onions into long strips a quarter to half an inch wide, and make the pepper strips and onion strips the same width so they cook at the same speed. Slice the onion from root to tip, not across, so the strips hold together in a hot pan. Slice the peppers from the inside, skin side down, after unrolling them into flat panels. Matched strips are what give you vegetables that are charred at the edges and tender in the middle, all at once.
Fajitas move fast once the skillet is hot. The cutting is where the dish is won.
Why the width matters
Fajita vegetables cook over high heat for six to eight minutes. In that time a thin strip chars and collapses, and a thick one stays raw in the middle. Aim the onion at a quarter to half an inch: thick enough not to burn, thin enough to soften.
The same logic applies between the two vegetables. If the onions are half an inch and the peppers a quarter, the peppers go limp before the onions are done. Pick one width, a third of an inch is a good middle, and hold both to it.
The onion: root to tip
Cutting an onion into rings gives you circles that fall apart into loose loops and scatter in the pan. Cutting from root to tip, along the onion’s natural lines, gives you long strips that keep their shape and soften evenly.
- Cut off the top of the onion, but leave the root end on.
- Halve the onion through the root and peel off the papery skin and the first tough layer.
- Lay each half flat side down. Cut a small V-shaped notch around the root to remove the hard core.
- Slice the half from root end to tip, angling the knife toward the center of the onion with each cut, like the spokes of a wheel. Each strip comes out the same width from inside to outside.
- Separate the strips with your fingers.
Angling the knife toward the center is the step most people skip. Straight parallel cuts give thin, wispy pieces from the edges and thick wedges from the middle. How to slice an onion for caramelizing shows the same pole-to-pole cut in detail.
Yellow and white onions both work. Red onion gives more color and a little sweetness.
The peppers: unroll, then slice
Most people slice a bell pepper by cutting it in half and working around the seeds. There is a cleaner way, and it gives long, flat strips.
- Cut off the top and bottom of the pepper, about half an inch each. Set them aside; the flesh around the stem can be diced later.
- Stand the pepper up. Make one vertical cut down one side.
- Lay it on its side, place the knife flat against the inside wall, and roll the pepper as you cut along the ribs. It unrolls into one long rectangular panel, leaving the core and seeds behind.
- Trim any white ribs from the inside of the panel.
- Turn the panel skin side down and slice it lengthwise into strips the same width as the onion.
Skin side down is important. A pepper’s skin is waxy and slick, and a knife skates across it. From the inside, the blade bites straight into the flesh.
Use three colors if you can: red and yellow peppers are sweeter, and green adds a slightly bitter, grassy note. One pepper of each, plus a large onion, serves four.
Poblanos and jalapeños
A poblano adds a gentle heat and a deeper flavor. Cut it the same way as a bell pepper. A jalapeño, if you want one, should be sliced thinner, into eighth-inch strips, because a little goes a long way and it should melt into the vegetables. Wash your hands with soap afterward; chile oil lingers.
Slicing the meat
The vegetables share the pan with steak or chicken, usually cooked first and sliced after. Skirt or flank steak should be sliced thin and against the grain after it rests; how to slice beef paper-thin explains how to find the grain and why the angle matters. For chicken, boneless thighs stay juicier than breasts over high heat, and how to cut chicken thighs into bite-size pieces covers trimming them.
Cut all the vegetables before the raw meat touches the board, then wash the board with hot, soapy water. It keeps the cleanup to one round.
Cooking
Heat a cast-iron skillet over high heat until it smokes lightly. Add a tablespoon of oil, then the onions. Give them a two-minute head start, since they are denser than the peppers, then add the peppers. Spread everything in a single layer.
Leave it alone for a minute or two between stirs so the edges char. Season with salt, a pinch of cumin, and a squeeze of lime at the end.
Crowding the pan steams the vegetables instead of charring them. If you are cooking for more than four, cook in two batches.
Setting up the board
Fajita prep produces a lot of volume: three peppers and an onion make a heaping pile of strips. Work on a large, stable surface, and slide finished strips to a bowl as you go so the board stays clear.
A 12 by 9 inch surface like the WONAMU. bamboo cutting board gives you room to unroll a pepper flat and slice it in one pass. A damp towel under any board keeps it from sliding; why your cutting board slides has the details.
The short version
Cut the onion in half through the root, remove the core, and slice from root to tip with the knife angled to the center. Cut the tops and bottoms off the peppers, unroll each into a flat panel, and slice skin side down. Make every strip the same width, a quarter to half an inch. Give the onions a two-minute head start in a smoking-hot skillet and do not crowd the pan.
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WONAMU. makes a bamboo cutting board designed for daily prep, 12 × 9 inches, bamboo, with a perimeter juice groove. Available on Amazon.
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