Using a vegetable peeler, remove 10 wide strips of zest from a ruby red grapefruit. (Take care to remove only the surface and not the white pith underneath.) Slice the zest into 1/4-inch-wide julienne strips. In a saucepan, cover the strips with 2 cups of water, bring to a boil and cook for 10 seconds. Drain in a strainer and rinse the strips under cold water.
Return the zest strips to the saucepan with 1/3 cup of sugar and 2/3 cup of water. Bring to a boil and cook, uncovered, until the mixture starts to thicken, about 8 minutes. At this point, the syrup should be a bit gooey and the zest strips should be almost transparent.
Spread 1/3 cup of sugar on a tray. Add the strips and toss, separating the pieces so that each strip is coated with sugar. Transfer the strips to a plate; let stand for at least half an hour, until dry. Store in the refrigerator in a jar with a tight-fitting lid.