Butterflying the shrimp gives it an attractive appearance and more surface area for the marinade to penetrate. Handle habaneros with care. They are among the hottest chiles, but marinating them in vinegar and sugar softens their bite.

Salsa:
1  tablespoon  sugar
2  tablespoons  lime juice
2  tablespoons  cider vinegar
1  tablespoon  fresh orange juice
1/8  teaspoon  salt
1/8  teaspoon  freshly ground black pepper
1/4  cup  finely chopped red onion
1  habanero pepper, cored, seeded, and finely chopped
1  tomatillo, finely chopped

Shrimp:
1  pound  large shrimp
1  tablespoon  lime juice
2  teaspoons  olive oil
1  garlic clove, minced
Dash of salt
Cooking spray

Prepare grill.

To prepare salsa, combine first 6 ingredients, stirring well with a whisk. Stir in onion, habanero, and tomatillo. Cover and let stand at room temperature 30 minutes.

To prepare shrimp, peel shrimp, leaving tails intact. Starting at tail end, butterfly each shrimp, cutting to, but not through, underside of shrimp. Combine 1 tablespoon of lime juice, 2 teaspoons oil, garlic, and dash of salt in a large bowl. Add shrimp; toss well. Cover and marinate in refrigerator 10 minutes.

Place shrimp, cut sides down, on grill rack coated with cooking spray, and grill for 5 minutes or until shrimp is done, turning once. Serve with salsa.