In a large mixing bowl, combine 2 tbsp olive oil, 3 tbsp freshly squeezed lime juice, minced garlic, 1/4 cup chopped cilantro, chili powder, cumin, 1/2 tsp salt, and 1/4 tsp freshly ground black pepper. Whisk the ingredients well to combine.

Add the peeled and deveined shrimp to the marinade. Toss gently to ensure all shrimp are evenly coated. Cover the bowl and refrigerate for at least 15 minutes, or up to 30 minutes. Avoid marinating longer than 30 minutes, as the lime juice can begin to chemically 'cook' the shrimp.

If using wooden skewers, soak them in water for at least 30 minutes prior to grilling to prevent them from burning. Thread the marinated shrimp onto the skewers, typically 3-4 shrimp per skewer, ensuring they are not packed too tightly.

While the shrimp marinates, prepare the avocado salad. In a medium bowl, gently combine the diced ripe avocados, halved cherry tomatoes, finely diced red onion, 1 tbsp freshly squeezed lime juice, 2 tbsp chopped cilantro, 1/4 tsp salt, and a pinch of black pepper.

Preheat your grill to medium-high heat (approximately 400-450°F or 200-230°C). Lightly oil the grill grates to prevent the shrimp from sticking.

Place the shrimp skewers on the hot grill. Grill for 2-4 minutes per side, or until the shrimp turn pink and opaque and are cooked through. Be careful not to overcook, as shrimp cook very quickly and can become rubbery.

Carefully remove the grilled shrimp from the skewers. Serve immediately alongside the fresh avocado salad. Garnish with extra fresh cilantro and lime wedges, if desired.