Mince the garlic and roughly chop the 1/2 cup cilantro for the marinade. In a bowl or container, combine the olive oil, chopped cilantro, 2.5 tbsp fresh lime juice, minced garlic, 1 tsp pepper, and 1/2 tsp salt. Add the peeled and deveined shrimp (tails on) to the marinade and toss gently to coat evenly. Cover and refrigerate for at least 30 minutes, though 1-2 hours is ideal for deeper flavor development. I find that marinating shrimp even for just 30 minutes makes a noticeable difference in the final taste—the acid from the lime starts to gently firm up the exterior.

While the shrimp marinates, finely chop the 1/2 cup cilantro for the sauce (aim for 1/4-inch pieces). Pit the avocados and scoop the flesh into 1-inch chunks. In a blender, combine the avocado chunks, finely chopped cilantro, 1/4 cup fresh lime juice, 1/4 tsp ground cumin, 1/2 tsp salt, and 1/4 tsp pepper. Blend until smooth, about 1 minute, scraping down the sides as needed. I prefer to blend the sauce just before serving rather than ahead of time—avocado discolors quickly, so this ensures the brightest green color and freshest taste on your plate.

Preheat your grill to medium-high heat (around 400°F if using a gas grill). Thread the marinated shrimp onto skewers, leaving a small gap between each piece for even heat exposure. Place the skewers on the hot grill and cook for 2.5-3 minutes on the first side without moving them—this develops a nice char and prevents sticking. Flip the skewers and grill for another 2.5-3 minutes until the shrimp are pink and cooked through (the flesh should be opaque and firm, not translucent). Remove from heat immediately, as overcooked shrimp becomes tough and rubbery.

Transfer the grilled shrimp to a serving platter. Drizzle or spoon the cilantro-lime avocado sauce from Step 2 over the shrimp, or serve it on the side as a dipping sauce. Serve immediately while the shrimp is still warm and the sauce is bright and vibrant.