While the chicken marinates, remove the stems, seeds, and white membranes from the bell peppers.
2-3 large bell peppers,
Thinly slice the peppers into strips.
Peel the onion.
1 large onion
Thinly slice the onion.
Cooking the Chicken
Heat the cast-iron skillet dry over medium-high heat for a few minutes, so that it gets very hot.
Pour the olive oil for cooking the chicken into the hot skillet.
2 tablespoons olive oil,
Lift the chicken breasts out of the marinade, letting the excess drip off.
Place the chicken breasts in the skillet: they should sizzle loudly as soon as they touch the bottom.
Don't overcrowd the skillet: if yours is small, cook the chicken in batches, otherwise it will steam instead of browning.
Cook for 3 to 5 minutes, until the underside is nicely browned.
Flip the chicken breasts.
Cook for another 3 to 5 minutes, until the chicken is golden and reaches 74°C in the center.
Remove the chicken from the skillet.
Let the chicken rest on a cutting board for a few minutes, so that it stays juicy.
Cooking the Peppers and Onion
Pour the olive oil for cooking the vegetables into the same skillet.
1 tablespoon olive oil,
Add the sliced peppers and onion.
Season lightly with salt, if desired.
Salt,
Cook, stirring occasionally, until the vegetables are lightly browned and softened.
While the vegetables cook, cut the chicken into strips 1 cm thick.
Assembling and Serving
Return the chicken strips to the skillet with the vegetables.
Toss together, if desired.
Let everything heat for a moment to warm the chicken back up.
Warm the tortillas.
8 flour tortillas
Serve right away with the warm tortillas and the toppings in small bowls: pico de gallo, guacamole, salsa, sour cream, lime wedges, and fresh cilantro.
Marinade: 20 to 30 minutes is enough. Don't go beyond 2 hours, as the lime juice eventually changes the texture of the chicken, which turns mushy. For a longer marinade (up to 2 hours), keep the chicken in the refrigerator and take it out 30 minutes before cooking.Chili powder: American "chili powder" is a mild blend of dried chiles, cumin, garlic, and oregano. The ground chile sold in Europe (cayenne pepper, "chili" or "chilli") is pure chile and much hotter: don't use it in the same amount. If you can't get American chili powder, use sweet paprika instead, with no more than a pinch of cayenne pepper for heat.Chipotle chile: this is smoked, dried jalapeño. If you can't find it, smoked paprika (pimentón) gives the smoky note, with a pinch of cayenne pepper if you want a little heat.Skillet: a cast-iron skillet holds its heat when you add the cold chicken, and that is what gives it the golden crust. Otherwise, a skillet with a thick base (3 to 5 mm) will do. The chicken must be well drained: too much marinade in the skillet makes the meat boil instead of searing.Chicken: boneless, skinless thighs make an excellent substitute for the breasts, and they stay juicier. You can cut the strips against the grain for more tender meat.Vegetables: there is no set cooking time for the peppers and onion in a skillet on the stovetop. Go by how they look: they are ready when they are lightly browned and softened. For the grilled version, allow 6 to 10 minutes in a skillet set on the grill grate.Tortillas: this recipe uses 15 cm flour tortillas, the "fajita" size. In supermarkets, you'll mostly find 20 cm flour tortillas, which work too. Sour cream: if you don't have sour cream, use thick crème fraîche or Greek yogurt.Grilled version: grill the whole chicken breasts over high heat until they are golden on both sides and reach 74°C in the center. Toss the peppers and onion with a little olive oil and salt, put them in a skillet set on the grill grate, and cook for 6 to 10 minutes, stirring often, until tender.Sheet-pan version: you can also spread the marinated chicken, peppers, and onion on a large sheet pan and roast them in the oven at 200°C for 20 to 30 minutes. You lose the well-seared crust from the cast-iron skillet, but it's simpler. Use a sheet pan large enough that nothing overlaps, otherwise everything steams.