1. Coffee Marinade: Brew 1 carafe of strong coffee (14 cups) in CRUX 14-Cup Coffee Maker to make 2 quarts. Turn Coffee Maker off and allow carafe and coffee to cool completely.
2. Whisk together coffee, brown sugar, mustard, vinegar, Worcestershire sauce, shallots, garlic, peppercorns and salt.
3. Grilled Flank Steak: In resealable bag, combine 2 cups Coffee Marinade with flank steak. Marinate in fridge for 24 hours, or freeze for up to 1 month (if frozen, thaw completely in fridge). Pour remaining marinade into resealable bags; freeze for future use.
4. Preheat grill to medium-high heat; grease grate well. Remove steak from marinade; shake off any excess marinade and discard. Brush steak with oil.
5. Grill steak, turning once, for about 10 minutes or until medium-rare. Sprinkle with salt. Let stand for 10 minutes before slicing thinly across the grain.