• 1 tablespoon vegetable oil
• 1 tablespoon minced onion
• 1 garlic clove, minced
• 7 ounces guava paste, chopped (3/4 cup)
• 1/2 cup water
• 1 tablespoon soy sauce
• 1 tablespoon ketchup
• 1 teaspoon cayenne pepper
• Salt
• Two 3/4-pound pork tenderloins
• Cilantro sprigs, for garnish

Heat the oil in a small saucepan. Add the onion and garlic and cook over moderate. heat, stirring, until softened, about 1 minute. Reduce the heat to low. Add the guava paste and water and cook, stirring, until the paste has dissolved, about 5 minutes. Stir in the soy sauce, ketchup and cayenne. Season with salt.

Set the pork tenderloins in a 9-by-13-inch glass baking dish and brush them all over with half of the guava glaze.

Light a fire or heat a grill pan over moderate heat. Grill the pork, turning and brushing with the remaining glaze, until browned on all sides and cooked through, about 15 minutes. Transfer the pork to a cutting board, cover loosely with foil and let stand for 10 minutes.