1 small onion, chopped
7 cloves garlic
½ cup olive oil
½ cup vinegar
½ cup soy sauce
2 tablespoons chopped fresh rosemary
2 tablespoons Dijon-style prepared mustard
2 teaspoons salt
1 teaspoon black pepper
Place onion, garlic, olive oil, vinegar, soy sauce, rosemary, mustard, salt, and pepper into the bowl of a food processor. Process until smooth. Place steak in a large plastic bag or dish. Pour marinade over steaks, seal or cover, and refrigerate for about 3 hours.
Preheat the BBQ. Brush grate with oil. Discard marinade, and place steak on the prepared BBQ. Cook as desired.