1. Place the cumin, peppercorns, coriander seed, caraway seeds, and cloves in a dry skillet. Place the skillet over medium heat, moving it to keep seeds from burning, until the seeds are aromatic, about 3 minutes. Transfer the seeds to a spice grinder, and cool slightly. Pulse until finely chopped but not powdery. Transfer the mixture to a bowl, and stir in salt, garlic powder, onion, and cilantro. Set the spice mixture aside.

2. Peel shrimp, leaving the tail and the last section of shell intact. Devein shrimp, and place in a bowl.

3. Heat a grill or grill pan over medium-high heat. Sprinkle spice mixture over the shrimp, and stir to coat. Grill the shrimp until opaque and cooked through, about 3 minutes on each side. Serve shrimp immediately with lime wedges.