Grilled Shrimp Skewers and Plantains

Name: Grilled Shrimp Skewers and Plantains
Ingredients: 1/4 cup plus 1 tablespoon extra-virgin olive oil, plus more for the grill; 1/2 small shallot, finely chopped; 1 tablespoon red wine vinegar; 1/2 cup chopped fresh cilantro (leaves and tender stems); 1/2 teaspoon ground cumin; 1/4 teaspoon dried oregano; Pinch of red pepper flakes; Kosher salt and freshly ground pepper; 1 1/2 pounds peeled and deveined jumbo shrimp; 2 Cubanelle chile peppers, seeded and cut into 1-inch pieces; 3 ripe plantains, peeled and halved lengthwise