Shell and devein the shrimp, then mince the garlic.

In a bowl, combine minced garlic, brown sugar, soy sauce, chili powder, lime juice, red pepper flakes, and 2 teaspoons of olive oil.

Add the shrimp to the bowl and toss to coat evenly.

Marinate the shrimp for 15 minutes.

Preheat the broiler.

Pit and peel the avocado, then cut it into 1-inch pieces.

Drain the marinated shrimp and arrange them in a single layer on a broiler pan rack.

Broil the shrimp about 4 inches from the heat for 2 minutes.

Using tongs, turn the shrimp over.

Broil for another 2 minutes, or until the shrimp is just cooked through.

Transfer the cooked shrimp to a bowl.

Add the avocado pieces, lemon juice, coriander, the remaining 2 teaspoons of olive oil, and salt and pepper to taste.

Gently toss everything together to coat.