Toss shrimp with cilantro, lime juice, garlic, and 2 tablespoons of the oil. Let stand at room temperature 1 hour.
Preheat grill to high (450°F to 550°F). Thread chorizo, poblanos, onion, and shrimp alternately onto skewers. Brush evenly with remaining 2 tablespoons oil; sprinkle evenly with salt and pepper. Grill, uncovered, just until shrimp turn pink and sausage and vegetables are charred, 4 to 6 minutes, turning once. Serve immediately with Tomatillo-Avocado Puree.