Reducing the grapefruit juice concentrates the flavor in the curd. You will need only part of it for the jasmine shortbread cookies, but you'll find plenty of ways to use up the remainder. Serve it with scones, biscuits, or pancakes; lighten it with whipped cream and fill tartlet shells; or dip cookies in it.
- 1 cup fresh Ruby Red grapefruit juice (from 2 grapefruits), plus 3 tablespoons finely grated Ruby Red grapefruit zest
- 3 large eggs plus 3 large egg yolks
- 1/4 cup plus 2 tablespoons sugar
- Coarse salt
- 4 tablespoons unsalted butter, cut into small pieces and softened
Bring grapefruit juice to a boil in a small saucepan over medium-high heat. Reduce heat and simmer until juice is reduced by half, about 5 minutes. Let cool.
Whisk together eggs, yolks, sugar, grapefruit juice, grapefruit zest, and a pinch of salt in a double boiler or a heatproof bowl set over (not in) a pot of simmering water. Cook, whisking constantly, until thickened, 6 to 7 minutes. Remove from heat, and whisk in butter, a few pieces at a time.
Pour mixture through a fine sieve into a bowl set in a larger bowl filled with ice water, and stir until cool. Cover surface of curd with plastic wrap, and refrigerate until cold, at least 4 hours and up to 2 days.