Turn broiler on high. Move broiler rack to top position. Prepare a baking sheet with foil. Thoroughly rinse produce and pat dry. Halve lime and juice. Peel and halve red onion. Cut halves into 1” dice. Cut end off romaine, halve lengthwise, then coarsely chop. Mince garlic. Halve grape tomatoes. Stem, seed, and cut green bell pepper into 1" dice. Rinse pineapple under warm water if still frozen. Mince 1 pineapple chunk. Rinse pork tenderloin and pat dry. On a separate cutting board, cut into 1 ¼” cubes.