Wash and dry the grapefruit.
Preheat the desired method of grilling now. For example: heat a sauté pan, grill pan, or outdoor BBQ grill to medium-high heat.
You can prepare the grilled grapefruit in multiple ways. Easily in a saute pan on the stovetop. In a grill pan on the stovetop. On any outdoor BBQ or grill. You can also choose to brûlée the grapefruit with a small cooking torch like you would with creme brûlée.
Then, prepare a small dish with 2 Tablespoons of sugar of choice spread out evenly on the dish. (Small dish: a small plate, a small bowl with a wide bottom, or a small saucer.)
Next, slice your grapefruit in half. You will then have two halves of grapefruit.
Place the grapefruit cut side down in the sugar. Press the sugar down firmly into the sugar to make sure all of the cut side of the grapefruit has an even and generous coating of sugar.
Place the sugared grapefruit cut and sugared side down in the pan or on the grill.
Let the grapefruit grill on medium-high heat until the sugar caramelizes.
Finally, remove grapefruit from the pan or grill once the sugar has caramelized, and then transfer it to the serving dish and serve.