To marinate the steaks, in a small bowl, whisk together the espresso, shallots, garlic, vinegar, oil, salt, paprika, and pepper. Arrange the steaks in a single layer in baking dish, pour the marinade evenly over them, and then turn the steaks to coat evenly. Cover the dish and refrigerate, turning the steaks once or twice, for at least 6 hours or up to overnight.