Combine olive oil, soy sauce, red wine vinegar, garlic, brown sugar, black pepper, and salt in a bowl to create the marinade.
Place the flank steak in a resealable bag and pour the marinade over it. Seal and refrigerate for at least 1 hour.
Preheat your grill or broiler to high heat.
Remove the steak from the marinade and let it come to room temperature for about 15 minutes.
Grill or broil the steak for 5-7 minutes on one side.
Flip the steak and cook for another 5-7 minutes, or until desired doneness.
Remove the steak from heat and let it rest for 10 minutes.
Slice the steak against the grain into thin strips.
Serve hot, garnished with fresh herbs if desired.