Step 1

If using wooden skewers, soak in water 30 minutes. Meanwhile, rinse shrimp; pat dry. Place shrimp in a resealable plastic bag set in a shallow dish. For marinade, coarsely chop garlic on a cutting board and sprinkle with salt. Using the side of a knife, mash garlic and salt to form a paste; transfer to a medium bowl. Stir in cumin, paprika, oregano, black pepper, and cayenne pepper until combined. Stir in grapefruit juice, lime juice, and olive oil.

Step 2

Pour 1/2 cup of the marinade over shrimp. Seal bag; turn to coat shrimp. Place mangoes in another resealable plastic bag set in a shallow dish. Pour 1/2 cup of the marinade over mangoes. Seal bag; turn to coat mangoes. Marinate shrimp and mangoes in the refrigerator 30 minutes. Cover and chill the remaining marinade until ready to serve.

Step 3

Drain shrimp and mangoes, discarding marinade. Thread shrimp onto skewers, leaving 1/4 inch between pieces. Grill shrimp, covered, over medium heat 3 minutes. Add mangoes; grill, covered, 5 minutes more or until shrimp are opaque and shrimp and mangoes are lightly charred, turning once (see Tip).

Step 4

To prepare the Grilled Corn-Avocado Salsa: Remove husks and silks from corn. Rub with olive oil and sprinkle salt and pepper. Grill corn, covered, over medium heat 20 minutes or until lightly charred, turning occasionally (see Tip). Cut kernels off cobs and place in a medium bowl. Stir in avocados, red sweet pepper, red onion, cilantro or basil, lime juice, red wine vinegar, and jalapeno chile pepper. Season to taste with salt and black pepper.

Step 5

To serve, line plates with salad greens and drizzle with the reserved marinade. Top with shrimp, mangoes, half of the Grilled Corn-Avocado Salsa, and, if desired, additional cilantro or basil. Pass the remaining salsa.