Pat the steaks dry and put them in a dish. Rub 1 tsp Cajun seasoning into each steak and set aside.
Peel and finely chop the onion. Pop it in a bowl. Finely dice the tomatoes and add to the onion. Finely chop the chilli, flicking out the seeds and white bits (they’re spicy). Finely chop the coriander stalks. Roughly chop the leaves. Add them all to the bowl. Grate in the lime zest. Squeeze in the juice.
Add 1 tsp cumin seeds to a dry frying pan. Toast for 1-2 mins till they smell nutty and aromatic. Add to the bowl with a pinch of salt. Stir everything together to make a salsa.
Separate the lettuce leaves and finely slice them. Pop them in a bowl or serving dish.
Halve the avocado. Scoop out the stone with a spoon, then scoop the flesh out of the skin. Roughly chop the avocado and put that in a bowl too (lots of serving bowls needed for this recipe).
Put the frying pan back on a high heat. Let it get smoking hot. Add ½ tbsp oil and the steaks. Fry for 1 min on each side. Transfer to a board. Loosely cover with foil and let them rest for 5 mins.
Unwrap the tortillas and put them on a plate. Slice the steaks into strips. Serve the tortillas with all the fillings and wrap and roll at the table.