Season the steak well on both sides with salt and freshly ground black pepper.
Finely chop 1 clove of garlic, add to a large bowl with a tablespoon of olive oil and the juice of half a lime. Add the seasoned steak to the bowl and use your hands to mix around in the marinade. When it’s well coated sit in the fridge for 30 mins to 3 hours.
Remove from the fridge before cooking and allow the steak to come to room temperature.
To make the salsa: cut the tomatoes into quarters, remove the seeds and roughly chop. Trim and halve the jalapeño and use a spoon to remove the seeds and roughly chop.
Finely slice the 2 spring onions, the coriander and a clove of garlic. Combine all of this in a bowl with the juice of half a lime, a tablespoon of olive oil, salt and freshly ground black pepper.
To cook the steak, remove it from the marinade and pat off any excess with paper towels. Put a pan over medium high heat and add a glug of olive oil.
When the pan is hot add the steak laying away from yourself. Cook for about 4 minutes on each side (or to your liking). When cooked transfer to a board and let it rest.
While the steak is resting heat the corn tortillas in a dry pan over high heat.
Cut the avocado in half, remove the stone and using the back of your knife carefully slice it in the skin then use a spoon to scoop out the slices. Sprinkle a little salt, pepper and lime juice over the slices (this will season it and also prevent it from turning brown).
Stir a pinch of salt into the sour cream.
When the steak is rested cut into thin slices against the grain, you may need to make an initial cut with the grain to make 2 smaller pieces that are easier to carve.
Serve the steak on a board with the heated tacos, salsa, sour cream, avocado and quartered limes.
