2tablespoonssoy sauce (or a gluten-free alternative)
1.5lbs.top round steak1 - 1.25 inches thick
1teaspoonDiamond Crystal kosher salt(not fine salt)
In a small bowl, whisk together the balsamic vinegar, soy sauce, mustard, garlic powder, and cumin. Place the steak in a Ziploc bag. Pour the marinade into the bag and rub it all over the steak. Seal the bag, removing as much air as possible. Place the bag on a plate in the fridge for at least 4 hours or overnight. If you're home while the steak is marinating, flip it once in a while.
Remove the steak from the fridge 1-2 hours before cooking, to allow it to reach room temperature.
Heat a well-seasoned cast iron skillet over medium-high heat until very hot, about 3 minutes.
Remove the steak from the bag and pat it dry with paper towels. Sprinkle it on both sides with salt and pepper. Place the steak in the hot skillet. Cook it for 3 minutes without moving. Flip to the other side (it should be deeply browned and slightly charred on the first side) and cook for 3 more minutes, again without moving it.
Using oven mitts, remove the skillet from the heat. Tent it with foil, and allow the steak to rest - and finish cooking from the skillet's heat - for 5 minutes.
Transfer the steak to a cutting board. Slice it very thinly and serve.
If you have a frozen top round steak, it's perfectly fine to marinate it while it's still frozen. I do it often. Simply place the frozen steak in a resealable bag with the marinade and place it in the fridge overnight.The best way to ensure that the steak is done to your liking is by using an instant-read thermometer. Rare is 120-130 degrees F (a warm red center). Medium-rare is 130-135 degrees F (mostly pink center with some red in the middle).The CDC recommends cooking meat, poultry, and eggs thoroughly.