Bursting with bold flavour, this Flank Steak with Chimichurri Sauce is a popular south American dish. Along with the zingy herb sauce, this steak is quickly seared making this an incredibly quick dinner.
Mix together the marinade ingredients (soy sauce, olive oil, red wine vinegar, mustard powder, pepper) in a casserole dish or high rimmed plate.
Trim any visible sinew from the flank steak and, if it's very large, cut in two pieces. Place into the marinade and chill for ½ an hour. Let it come to room temperature for 1/2 an hour before cooking (giving it a total marinating time of 1 hour).
Finely chop the onion, chilli and herbs and combine in a bowl with the vinegar, salt, and garlic. Whisk well. While whisking, drizzle in the oil until all fully combined.
Heat a tablespoon of oil over medium-high heat in a large frying pan, skillet or alternatively you can use a grill or BBQ but do not pour oil over. Once it starts smoking, gently place the steak in the pan.
Sear for two minutes, then turn over for another 2 minutes. Depending on the thickness of your steak, keep flipping it until the outside is nicely charred and the inside is medium-rare. Medium rare will register 65C / 150F on a meat thermometer.
Remove the steak from the pan, and allow it to rest for 5 minutes.
Use a very sharp carving knife to carefully slice the steak very thinly (2-3mm thick), across the grain. Lay it out on a platter, spoon the sauce over the top and place in the middle of the table for everyone to dig in.
I use an Australian standard 20ml tablespoon (equal to 4 teaspoons)
If you prefer to skip the marinade, just season the meat with 1 teaspoon of salt and 1 teaspoon of pepper right before cooking.