1 ½ cups fresh grapefruit juice (360 ml)
3 tbsp. cornstarch, sifted (7 gr)
3/4 cup sugar (150 gr)
In a small saucepan, whisk together grapefruit juice and cornstarch. Bring to a simmer, and continue whisking until the mixture gels, about 3-4 minutes. Remove from heat, and add the sugar, whisking to combine well. Pour into a clean glass jar. Cool completely to room temperature before storing in the refrigerator. Best when made a day in advance of using.