In a medium bowl or large liquid measuring cup,, mix the oil, lemon juice, balsamic vinegar, soy sauce, liquid honey, Dijon mustard, minced garlic, and black pepper.
Place the flank steak in a shallow glass dish or a sealing plastic Ziploc bag. Pour the marinade over the steak, turning the meat to coat thoroughly. Cover, and refrigerate overnight. If you want, you can also marinate for a full 24 hours with great results.
Preheat your grill to a medium-high heat.
Oil the grill grate on your BBQ . Place the flank steaks on the grill, and discard the marinade. Grill the flank steak for 5 minutes per side, or to desired doneness.
Remove and place on a plate. Let rest for 5 minutes, then slice against the grain and serve.
Notes
As with all marinade recipes, the nutritional calculator calculates the entire marinade not the smaller amount that the steak absorbs in the end. Calories are no accurate and are for the entire sauce and steak.