I simply love to make curds; they can be used as a filling for pies, tarts, cakes and cookies, adding so much fresh flavor and dimension. We add butter to ours, but the timing and how you add it makes a big difference. After making, thin any curd recipe with 1/4 to 1/2 cup simple syrup to the desired consistency to make a tangy dessert sauce, delicious served over toasted pound cake, topped with vanilla ice cream. The flavors of grapefruit, scented with vanilla are heavenly.
FROSTING, ICING, ETC RECIPE HELP

Recipe used with the:
Toasted Pound Cake with Grapefruit and Vanilla Curd 

INGREDIENTS
Grapefruit Sugar:
2/3 cup sugar
2 tablespoons grapefruit zest (peel)
Seeds scraped from 1/2 vanilla bean

Remainder of recipe:
3 large eggs
4 large egg yolks
1/2 cup freshly squeezed grapefruit juice, from about half a large grapefruit
1/4 cup freshly squeezed lemon juice, from about 1 large lemon; preferably Meyer lemon
4 tablespoons (1/2 stick) unsalted butter, chilled and cut into small cubes

NOTES:
Always zest a grapefruit, or remove its peel before squeezing it for its juice! Always strain the juice to remove any seeds before using.
More How To.

Extract the vanilla seeds: More How To

INSTRUCTIONS
Make the Grapefruit Sugar:
1. In a food processor fitted with a steel blade, pulse together the sugar, grapefruit zest, and vanilla seeds, until the sugar is yellow and very fragrant. This will make Grapefruit Sugar.
NOTE: This process will scratch the bowl of your food processor. Alternatively, use a small bowl with a fork to blend the ingredients together.

Make the rest of the recipe:
1. Have a fine-mesh strainer, suspended over a bowl, ready near the stove.

2. Prepare a double boiler: Pour a few inches of water into a medium heavy-bottomed saucepan. Fit a heat-proof glass bowl over the top, making sure it does not touch the water below. Remove the bowl. Bring water to a simmer over medium heat.

3. Combine the grapefruit sugar, eggs and egg yolks in the medium heatproof bowl. Whisk together for one minute to distribute the sugar.

4. Fit the bowl back over the saucepan with the simmering water and whisk constantly for about 30 seconds, or until the sugar is dissolved.
SARAH SAYS: To see if the sugar has dissolved, feel mixture between your thumb and forefinger. If you feel large grains of sugar, continue to whisk until they feel small.

5. Add the grapefruit and lemon juices and whisk. Cook, whisking frequently, until the curd reads 170 degrees F and has the consistency of sour cream, about 10 minutes. Remove the bowl from the heat.
Strain the curd through a fine-mesh strainer into the bowl.

6. Let the mixture cool to body temperature – about 98 degrees F.

7. Whisk in the softened butter, one tablespoon at a time with an Immersion Blender or quickly, with a wire whisk until well blended.
SARAH SAYS: Make sure you really whisk in the butter quickly, otherwise the curd will be greasy.

STORAGE
1. Press a piece of plastic wrap on its surface and cut 6 small steam vents in the plastic to cool. Refrigerate the curd, preferably overnight, to thicken.

2. Then, store in the refrigerator in an airtight container and consume within 1 week. The curd can be frozen for up to 1 month without quality changes when thawed.
To thaw, move the container from the freezer to a refrigerator for 12 – 24 hours before intended use.