Grapefruit Curd

Directions

1. 1
   Combine yolks, grapefruit juice, lemon juice, half of the zest, and the sugar in a heavy-bottom saucepan; whisk to combine.
2. 2
   Cook over medium-high heat, stirring constantly with a wooden spoon (be sure to scrape the sides of the pan), until the mixture is thick enough to coat the back of the spoon, 8 to 10 minutes, and registers 160F on an instant-read thermometer.
3. 3
   Remove saucepan from heat.
4. 4
   Add salt and butter, one piece at a time, stirring until smooth.
5. 5
   Strain through a fine sieve into a medium bowl.
6. 6
   Stir in the remaining zest.
7. 7
   Cover with plastic wrap, pressing it directly onto the surface of the curd to prevent a skin from forming.
8. 8
   Refrigerate until chilled and set, at least 1 hour or up to 1 day.