Mojo Pork Kebabs with Plantains

Name: Mojo Pork Kebabs with Plantains
Ingredients: 1 1/4 to 1 1/2 pounds pork tenderloin, cut into 3/4-inch cubes; 1 red onion, cut into 1-inch chunks; Kosher salt and freshly ground pepper; 5 cloves garlic, minced; 1/2 cup fresh orange juice (from 1 to 2 oranges), plus 8 small orange wedges; 1/4 cup fresh lime juice (from 2 limes); 1 teaspoon dried oregano; 1 teaspoon ground cumin; 1/3 cup plus 1 tablespoon extra-virgin olive oil, plus more for the grill; 2 ripe plantains, sliced into 1/2-inch rounds; 2 tablespoons chopped fresh cilantro