Heat your grill to medium-high heat. Grill the pineapple directly, for 2 to 3 minutes per side. Remove from the grill to cool while you prepare the rest of the salsa. In a medium bowl, toss together the red jalapeno, red onions, cilantro, lime juice, a big pinch of salt and pepper. Chop the cooled pineapple and add to the salsa. Chill while you grill the panela.