Step 1: Twist the crown (leafy top) off the pineapple and set it aside, if desired, for garnish, or cut it off with a sharp knife). Trim a thin slice off the top (if you’ve twisted the crown off) and the bottom so the pineapple sits level. Cut the rind off the pineapple. Cut into 1/2-inch thick slices; core each slice with a knife or appropriately sized cookie or biscuit cutter, or the wide end of a large metal pastry tip.
In a medium bowl, combine the wine and honey and whisk to mix.
Step 2: Arrange the pineapple slices in a large nonreactive baking dish. Pour the wine-honey mixture over the pineapple and marinate in the refrigerator for at least 4 hours or as long as overnight, turning the slices a few times so they marinate evenly.
Step 3: In a small bowl, combine the cornstarch and water and whisk or stir until smooth. Add to a heavy saucepan. Strain the marinade into the saucepan and stir into the cornstarch mixture. Bring to a boil, and cook until thick and syrupy: you should have about 1 cup. Set the syrup aside and let cool.
Step 4: Set up your grill for direct grilling and preheat to high. Brush and oil the grill grate.
Step 5: If using the sugar, dip each pineapple piece in the sugar, crusting both sides, shaking off the excess. Arrange the pineapple slices on the grill grate. Grill until golden brown on both sides, 2 to 4 minutes per side.
Step 6: Transfer the pineapple slices to ice cream-filled bowls or a platter. Pour the Muscat syrup on top. Lightly sprinkle the fruit with coarse salt. Garnish with the pineapple crown or fresh mint sprigs and serve at once.