In a small bowl, combine instant espresso (or coffee), paprika and salt.
Rub the mixture into steak and place it in a large zipper-topped plastic bag; pour red wine vinegar and olive oil on top.
Seal bag and turn to coat; refrigerate overnight or for at least 5 hours.
Preheat outdoor grill to MEDIUM-HIGH. Remove steak from marinade, discarding marinade and bag; grill for 4 to 5 minutes per side (depending on thickness) or until the desired level of doneness is achieved.
Transfer grilled steak to a cutting board and allow it to rest for 5 minutes; thinly slice across the grain (diagonally).