If using wooden skewers, soak in cool water for at least 30 minutes prior to cooking. If needed, cut down the soaked skewers to fit the size of your grill pan or skillet.
Thaw the shrimp completely and dry with paper towels. Add to a large bowl and toss with 2 tablespoons extra virgin olive oil.
Stir together the brown sugar, smoked paprika, chipotle chili powder, garlic powder, onion powder, cumin, black pepper, and a pinch of koshers alt. Sprinkle onto the shrimp and toss to combine.
Thread 4-5 shrimp onto your skewers. The number depends on the size of your skewers and shrimp.
Heat the grill pan, grill, or skillet over medium-high heat. Working in batches as needed, cook the shrimp for 2-3 minutes per side until nicely charred and opaque. Remove from heat and immediately brush with barbecue sauce. Repeat as needed with the rest of the shrimp skewers.
To make the garlic sauce, mix together the mayo, Greek yogurt, lemon juice, garlic cloves, and a pinch each of salt and pepper. Taste and adjust seasonings as needed.
Pile rice into a shallow bowl. Top with skewers, sliced avocado, cucumber, and pickled onions, as desired. Drizzle garlic sauce and finish with fresh basil, or another favorite herb.