Place you index finger on the top of a grapefruit stem area and cup your hand around it from top to bottom. Then cut it in half directly through the middle. (If you don't see a flower pattern, you cut the grapefruit in the wrong direction.) Cut each grapefruit this way.
Use a small serrated knife to cut around the inside rim of each grapefruit half, separating the fruit from the skin. Then cut along the membrane between each little triangular segment, so that each bite comes out easily with a spoon. Leave intact.
One at a time, sprinkle 1 teaspoon of granulated sugar over the top of each grapefruit half. Then hold the torch over the grapefruit and brulee the top until the sugar turns golden and has candied the top of each half. This should take 30-60 seconds per half. Serve immediately and repeat.