Mix the marinade: In a bowl, combine the juice of 2 limes, 1 teaspoon lime zest, garlic, chili powder, cumin, smoked paprika, oregano, soy sauce (if using), 1 tablespoon oil, and 1 teaspoon salt. Whisk until smooth.
Marinate the steak: Pat the steak dry.
Add it to a zip-top bag or shallow dish and pour in the marinade. Turn to coat. Let it sit for 20–30 minutes at room temperature (or up to 2 hours in the fridge).
Don’t go much longer or the citrus can toughen the meat.
Start the rice: Rinse the rice until the water runs mostly clear. In a saucepan, warm 1 tablespoon butter or oil. Add rice and toast for 1 minute.
Pour in water or broth, add a pinch of salt, bring to a boil, then reduce to low, cover, and cook 12–15 minutes until tender.
Prep the veggies: While the rice cooks, thinly slice the bell peppers and onion. Toss with 1 tablespoon oil and a pinch of salt and pepper.
Cook the steak: Heat a large cast-iron skillet or grill pan over high heat until very hot. Add 1 tablespoon oil.
Remove steak from marinade (shake off excess) and sear 3–5 minutes per side for medium-rare, depending on thickness. Transfer to a board to rest for 5–10 minutes.
Sauté the peppers and onions: In the same hot pan, add peppers and onions. Cook over medium-high heat, stirring occasionally, until softened with charred edges, about 6–8 minutes.
Squeeze in a little lime juice and season with salt and pepper.
Finish the rice: Fluff rice with a fork. Stir in the juice of 1 lime, 1 teaspoon lime zest, and about 1/4 cup chopped cilantro. Taste and add salt if needed.
Slice the steak: Slice thinly against the grain at a slight angle for tenderness.
Toss the slices with any resting juices.
Warm the tortillas: Heat tortillas in a dry skillet for 15–20 seconds per side, or wrap in foil and warm in a low oven. For extra flavor, char them briefly over a gas flame with tongs.
Assemble and serve: Pile steak and vegetables into warm tortillas. Add a scoop of cilantro-lime rice on the side or tuck some into the fajitas.
Garnish with extra cilantro, a squeeze of lime, and your favorite toppings.