Step 1Using a spice grinder or mortar and pestle, crush the peppercorns with the coffee beans and fennel seeds. Place in a small bowl and mix with the chili powder, cinnamon and salt.
Step 1Whisk together the Tia Maria or coffee liqueur and the Worcestershire sauce in a small bowl.
Step 2Trim the steaks of any excess fat and cut each steak in half. Place the steaks in a large, resealable plastic bag and pour in the marinade. Press the air out of the bag and seal tightly. Turn the bag to distribute the marinade, place on a plate and refrigerate 2 to 4 hours, turning occasionally.
Step 3Remove the steaks from the bag and discard the marinade. Pat the steaks dry with paper towels. Coat both sides of the steaks with the rub. Allow them to stand at room temperature for 20 to 30 minutes before grilling.
Step 4Heat the grill on high heat.
Step 5Brush or spray both sides of the steaks with olive oil. Season with additional salt to taste. Grill them over direct heat 3 to 5 minutes, turning once halfway through grilling time. Remove them from the grill, squeeze lime juice over them, if using, and allow to rest 2 to 3 minutes. Serve warm, whole or thinly sliced.