1. Peel and devein the shrimp, leaving the tails intact. Place the garlic and spices in a large bowl and mash to a paste with the back of a wooden spoon. Stir in the lime juice and shrimp and marinate for 30 minutes, stirring once or twice.
2. Combine the ingredients for the salsa in a mixing bowl and toss to mix. Correct the seasoning, adding salt, lime juice, or sugar to taste. The salsa should be highly seasoned.
3. Preheat your barbecue grill or broiler to high. Drain the shrimp and skewer on metal or bamboo skewers. Grill the shrimp until cooked, 1 to 2 minutes per side. Serve on plates on rice with the salsa on the side.