Shrimp adobo with mango black bean salsa

1-1/2 pounds jumbo shrimp
for the adobo marinade:
4 cloves garlic, minced
1 teaspoon each cumin, dried oregano, salt, and pepper
3/4 cup fresh lime juice
For the salsa:
2 cups diced ripe mango or papaya
1 cucumber, peeled, seeded, and finely diced
3/4 cup cooked, rinsed, drained black beans
1/4 cup diced red or yellow bell pepper
1/4 cup diced red onion
1/2 to 1 scotch bonnet, seeded and minced (optional)
1/4 cup chopped fresh cilantro
3 to 4 tablespoons fresh lime juice, or to taste
1 tablespoon brown sugar (optional)
a pinch of salt

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.