1. Turn on the oven broiler. I set mine at high temperature.
2. Using a pairing knife, cut all the way around the grapefruit and between the fruit and the rind. Try not to cut all the way through the bottom rind, you want to keep the juices. Drizzle agave nectar lightly over the grapefruit halves. Sprinkle with turbinado sugar.
3. Place the grapefruit halves on a baking sheet. Put in the oven, under the broiler for 2-3 minutes, just until the sugar is bubbling and crystallized.
4. Serve warm.
*Note-you can use honey instead of agave or brown sugar instead of turbinado sugar.*