In a glass measure, whisk together olive oil, vinegar, ginger, garlic, salt, cinnamon, coriander, paprika, sugar, cumin, pepper, and cayenne.
Rinse flank steak and pat dry; put in a 1-gallon zip-lock plastic bag. Pour in all but about 3/4 cup of the marinade (save remaining for Grilled Eggplant and Pepper Salad); seal bag and turn to coat meat well. Chill for at least 4 hours and up to 1 day.
Lift steak from marinade (discard used marinade) and lay on a well-oiled grill over a solid bed of medium-hot coals or medium-high heat on a gas grill (you can hold your hand 1 to 2 in. above grill level only 3 to 4 seconds); close lid on gas grill. Cook steak, turning occasionally, until browned on both sides and still pink in the center (medium-rare; cut to test), 10 to 12 minutes total.
Transfer steak to a platter or rimmed board and let rest 5 minutes. Then cut across the grain into thin, slanted slices.
Note: Nutritional analysis is per serving.