Place your grapefruit on a sheet tray lined with foil. Place 1 tbsp. of brown sugar on top of each grapefruit half. Spread the sugar over the top of the exposed grapefruit. Use a blowtorch to lightly caramelize the sugar until it has melted and turned a deep caramel color. Alternatively, you can place under your oven broiler set to HI for 3 to 5 minutes or until the sugar bubbles and caramelizes. Let the grapefruit cool at room temperature and set aside.

In a small bowl combine ½ cup of the soy milk and the cornstarch and whisk until the cornstarch dissolves completely, set aside. In a medium saucepot combine the rest of the soy milk, coconut milk, vanilla, and agave syrup.

Pour in the mixture of soy milk and cornstarch into the saucepot. Bring to a very light simmer over low-medium heat. Be sure to stir constantly to avoid the cornstarch sticking to the bottom and burning. Keep stirring until the mixture will thickens enough to coat the back of your spoon. Remove from the heat and set aside to cool slightly. Pour into a heat-proof container and let cool in the fridge for at least four hours.

Over a small bowl, juice the broiled grapefruit. Some of the pulp and caramelized sugar will fall into the bowl, but that’s ok. Be sure to remove the seeds, but don’t strain the juice. Place in the fridge and let cool completely.

In a blender, combine the grapefruit juice, gelato base, food coloring, and Grand Marnier. Blend until completely smooth. Churn in your ice cream machine according to the manufacturer’s instructions.

Once it is done churning, place in a freezer-safe container. Chill the mixture in the freezer for 3 hours.