Forget the grill and cook Rosemary and Balsamic Marinated Steak under the broiler for a simple, winter steak dinner.
In a large bowl or freezer bag, combine the chopped rosemary, balsamic, dijon, garlic cloves, lemon zest and juice, olive oil, and chili flakes and salt and pepper if using. Mix well to combine.
Cut the flank steak into 2-4 smaller pieces, depending on the size of your steak. This will make the steak easier to slice down the road. Add the flank steak to the marinade and completely submerge. Allow the steak to marinate for 20 minutes, or up to 2 hours.
5 minutes before you are ready to begin cooking, arrange the oven rack at the top of the oven, and turn the broiler on to High to give the broiler time to preheat. Meanwhile remove the steak pieces from the marinade and wipe off most of the marinade (although I actually prefer to cook the steak with some of the herbs and spices remaining for added flavor). Place the steak on an aluminum foil lined baking sheet or roasting pan.
Broil for 4 minutes on High. Flip the steak pieces, and then broil for another 3 -4 minutes for medium rare.
Remove from the oven and let the steak rest for 10 minutes. To serve, slice against the grain on a bias. Sprinkle with thyme and flaky sea salt.