To begin the process of marinating the meat, pat off the steak with a paper towel and prick the flank steak with a knife on both sides to tenderize.
Coat the meat in a liberal amount of soy sauce and Worcestershire sauce and rub them both into the flank steak (this also gives the grill seasoning something to stick to).
Then season with grill seasoning, flip the steak and do the same to the other side. Place in a plastic bag and return to the refrigerator.
Let the steak marinate for 4-6 hours.
Slice peppers and onions into strips, then season with olive oil, salt, and pepper.
Sauté in either a skillet on the stove or place in a grill basket on the grill.
Before grilling, take the flank steak out of the refrigerator for about 10 minutes to take the chill off.
Place on a crazy hot grill and cook to your preference (we prefer to sear steaks on a really hot grill, it produces a well-caramelized exterior and ensures that the steak isn’t over done in the center).
We prefer our steaks medium-rare, so 3-4 minutes on each side on a hot grill should get you there. Pull peppers, onions, and meat off the grill and let rest on a warm plate tented with foil for 10 or so minutes.
Slice the steak against the grain and serve on warm flour tortillas.