1 beef flank steak (about 1-1/2 to 2 pounds) or beef top round steak, cut 1 inch thick (about 1-3/4 pounds)
1/3 cup fresh lime juice
1/4 cup chopped fresh cilantro
1 tablespoon packed brown sugar
2 teaspoons minced chipotle chilies in adobo sauce
2 tablespoons adobo sauce (from chilies)
2 cloves garlic, minced
1 teaspoon freshly grated lime peel
Combine marinade ingredients in small bowl; mix well. Place beef steak and marinade in food-safe plastic bag; turn steak to coat. Close bag securely and marinate in refrigerator 6 hours or as long as overnight.
Remove steak from marinade; discard marinade. Place steak on grid over medium, ash-covered coals. Grill flank steak, uncovered, 17 to 21 minutes for medium rare to medium doneness (top round steak 16 to 18 minutes for medium rare doneness; do not overcook), turning occasionally. Carve steak across the grain into thin slices. Season with salt, as desired.