Soak 1 dozen small bamboo skewers in cold water. Cut off top and bottom poles of pineapple. Stand it upright on the cutting board and cut off rind, using a sharp knife and smooth downward motions. Remove any remaining eyes with the tip of a paring knife. Cut in quarters lengthwise and cut out and discard woody core. Cut flesh into 1 or 1 1/2-inch chunks.
In a medium bowl, combine tequila, lime juice and sugar. Add pineapple chunks and toss to coat. Let marinate 30 minutes at room temperature. Preheat grill to medium high. Drain pineapple chunks and divide among skewers. Brush grill well, wipe with oiled paper towel and place skewers on grill at an angle. Cook a total of 68 minutes, turning frequently, until outside is lightly caramelized. Remove from grill, let cool slightly and serve 2 skewers in each bowl of Watermelon Granita.
c.1996, M.S. Milliken & S. Feniger, all rights reserved