Combine 1/2 cup molasses, 1/4 cup mustard, and 1 tablespoon olive oil in a shallow dish or large zip-top plastic freezer bag. Add steaks; cover or seal, and chill at least 2 hours, turning occasionally. Remove steaks from marinade, discarding marinade. Sprinkle steaks evenly with salt and pepper.
Grill, covered with grill lid, over medium-high heat (350° to 400°) 5 to 7 minutes on each side or to desired degree of doneness.