Wash the grapefruits. Using a paring knife, cut each grapefruit in half crosswise. If you prefer segments removed from the membrane, use a sharp paring knife to cut along the membranes and free the segments (supreming). Otherwise leave the flesh in the halved shell for a rustic presentation.

Loosen the flesh

Use a small spoon or grapefruit knife to gently loosen the flesh from the rind and slightly raise the pulp so the surface is even and slightly domed. This gives a flat surface for the sugar and allows even caramelization.

Optional flavoring

If using, spoon 1/4 teaspoon vanilla extract and 1 teaspoon orange liqueur over each grapefruit half (so 0.5 tsp vanilla and 2 tsp liqueur total). Allow to sit 2–3 minutes so flavors soak in. If you like a hint of salt, sprinkle a very small pinch of sea salt on each half now.

Sugar the surface

Evenly sprinkle 2 teaspoons of granulated sugar onto the cut surface of each grapefruit half (total 4 tsp). For a finer, glassier crust, optionally dust a thin layer of caster sugar over the granulated sugar and gently tap off any excess.

Torch to brûlée

Hold the kitchen torch about 2–3 inches (5–8 cm) from the surface and move it continuously in slow circles to melt and caramelize the sugar. Work until the sugar bubbles, darkens to amber, and forms a glossy, crisp shell — about 20–45 seconds per half depending on torch and sugar thickness. Be careful not to burn the edges; keep the torch moving.

Rest and set

Let the brûléed grapefruit halves rest 1–2 minutes so the caramel hardens. If the sugar cracks too early, allow 30–60 seconds more for full setting.

Garnish and serve

Place each brûléed half in a serving bowl or coupe. Garnish with 4 mint leaves per half arranged on the side or lightly pressed into the set sugar. Serve immediately so you get the contrast of chilled grapefruit and crisp caramel top.

Tools and Finishing

If you do not have a kitchen torch: preheat your oven broiler to high and place grapefruits on a baking sheet cut side up about 6 inches below the broiler. Watch constantly and broil for 1–3 minutes until the sugar melts and caramelizes — this method is faster and more prone to uneven browning, so monitor closely and rotate as needed.

Clean the torch tip after use per manufacturer instructions. Serve the brûléed grapefruit immediately for best texture; if you must hold for a short time, keep them refrigerated briefly but re-crisping with a quick torch pass just before serving is recommended.