1 1/2 to 2 pounds flank steak
2 to 3 tablespoons lemon juice, lime juice, vinegar, or other acid
2 tablespoons olive oil
3 cloves garlic, optional
1 teaspoon salt
1 to 2 teaspoons spices, like chili powder, barbecue spices, curry, or other favorite spice blend
Marinate for 1 hour or up to 24 hours: Cover the dish and place the steak in the fridge for at least 1 hour or up to 24 hours. Flip the steak occasionally if you happen to think about it.
Heat the broiler and prepare the pan: Set your broiler to its highest setting (or simply turn it on if it doesn’t have settings). Place an oven rack a few inches below the broiler element. Line a broiler pan with aluminum foil, add the top, and spray the top with nonstick cooking spray.
Broil the steak 4 to 6 minutes per side: Remove the steak from the marinade, shake off any excess, and place it in the middle of the broiler pan. Slide it directly under the broil. Cook for 3 minutes each side, then 2 minutes each side.
Check the steak for doneness: The steak is done when the edges are charred and crispy, and you see some nicely dark searing on the top.
Rest for 5 minutes (preferably 10): Transfer the steak to a cutting board and rest for 5 minutes.
Slice against the grain: Slice the steak into very thin slices using a sharp knife, cutting against the grain. This means the long fibers should all be running left to right on your cutting board, and you should be slicing through them, top to bottom.
Chimichurri: parsley, olive oil, red wine vinegar, salt, pepper, red chili flakes (garlic, optional)