Special Equipment: Blowtorch
Halve each grapefruit crosswise, and cut a thin slice off the bottom of each half to stabilize the pieces. Remove all seeds from the grapefruit, and loosen the segments with a paring knife.
Sprinkle each half evenly with the sugar. Using a blowtorch, melt the sugar to form a golden brown and crispy surface. Sprinkle the hot sugar with the salt, and serve immediately.