Whisk soy sauce, olive oil, Worcestershire, lemon juice, brown sugar, Dijon, garlic, pepper, and flakes in a bowl.
Pat steak dry. Place in a large zip-top bag or shallow dish.
Pour in the marinade, press out excess air, and seal. Turn to coat well.
Chill at least 30 minutes and up to 8 hours, flipping halfway for even marinating.
Preheat grill to high heat and oil the grates. Remove steak and shake off excess marinade; discard used marinade.
Grill 3–5 minutes per side to desired doneness. Rest 5 minutes, then slice against the grain and serve.