Make the marinade and season the steak: In a shallow bowl combine 1 tablespoon olive oil, 1 teaspoon chipotle powder, minced garlic, zest of 1 lime and juice of 1 lime (about 1–2 tablespoons), 1/2 teaspoon kosher salt and 1/4 teaspoon freshly ground black pepper. Whisk to combine. Coat the 400 g flank or skirt steak with the marinade and let rest at room temperature for 15–20 minutes. Why: the acid and salt in the lime juice begin to tenderize and flavor the surface while the chipotle brings smoky heat; giving the steak a short rest at room temperature helps it cook evenly.

While the steak marinates, make the pico de gallo: Combine the diced tomatoes, 1/2 finely diced red onion, seeded & diced jalapeño (adjust seed amount to taste), and half the chopped cilantro (about 1/2 cup). Add the juice of 1/2 lime, a pinch of salt, and 1/4 teaspoon black pepper. Stir and taste. Why: assembling the pico now lets the flavors marry; lime brightens the tomatoes and salt amplifies sweetness and balances the heat.

Prepare the guacamole: Halve and pit the avocados, scoop the flesh into a bowl and mash lightly with a fork — leave some small chunks for texture. Add the remaining chopped cilantro (about 1/2 cup), juice of the remaining 1/2 lime, a pinch of salt and a tiny pinch of chipotle powder if you like more smoke. Mix and taste. Why: mashing gently keeps a creamy texture with pleasant avocado bite; the lime prevents browning and layers in the citrus note that ties to the steak.

Preheat your grill, grill pan or cast-iron skillet to high. Pat the steak dry (this helps develop a better sear) and brush or rub with the remaining 1 tablespoon olive oil. Why: a very hot surface gives the Maillard crust that adds deep, savory flavor and contrast to the creamy guacamole.

Sear the steak: Place the steak on the hot grill or pan and cook 3–4 minutes per side for medium-rare (internal temp ~130–135°F / 54–57°C), 5–6 minutes per side for medium. Let the steak sear without moving it so a good crust forms. Why: quick, high-heat cooking is ideal for thin cuts like flank or skirt because it creates a crust quickly while keeping the center tender; overcooking makes them tough.

Rest and slice the steak: Transfer the steak to a cutting board and let it rest 6–8 minutes (tent loosely with foil). Then slice thinly across the grain into long ribbons. Why: resting lets juices redistribute so they don’t run out when you cut, and slicing against the grain shortens muscle fibers, making each bite tender.

Warm the lettuce leaves: If you prefer, very quickly char the romaine leaves on the grill (10–15 seconds per side) or dip in hot water for a few seconds to soften. Otherwise serve crisp. Why: warming or lightly wilting the leaves makes them more pliable for wrapping without losing their crunch.

Assemble the tacos: On each lettuce leaf place a spoonful of guacamole, a few slices of steak, and spoon over the pico. Finish with a drizzle of any resting juices, a sprinkle of fresh cilantro, and an extra squeeze of lime to taste. Why: layering maintains contrast (cream, meat, bright salsa) and a final squeeze of lime elevates the flavors.

Serve immediately: These are best eaten right away while the steak is warm and the guacamole is fresh. Leftovers can be kept separately (steak sliced and chilled; salsa and guac refrigerated) for up to 2 days. Why: textures and contrasts are at their peak immediately after assembly; stored together guacamole eventually browns and lettuce soggifies.