Cook the rhubarb:Add chopped rhubarb, 1 tablespoon of water, and ¼ cup of the sugar to a small saucepan. Cook over medium heat for 10-15 minutes, stirring occasionally, until the rhubarb is fully broken down and very soft.
Add natural color:Stir in the dragonfruit powder until evenly combined. Remove from heat.
Blend:Transfer the rhubarb mixture to a high-speed blender and blend until completely smooth. Set aside.
Whisk the egg yolks:In a medium mixing bowl, whisk the egg yolks with the remaining ½ cup sugar and a pinch of salt until thick and slightly lighter in color.
Temper the yolks:Slowly add the warm rhubarb puree to the yolk mixture, about ¼ cup at a time, whisking constantly. Continue until all of the rhubarb is incorporated and the mixture is smooth.
Finish with butter:Add the butter pieces and whisk until fully melted and the curd is shiny, silky, and velvety. No additional cooking required.
Cool and store:Transfer the curd to a clean jar or container. Let cool completely, then store in the fridge.
Notes
This recipe makes 2 cups of curd - nutrition analysis is assuming 1/4 cup per serving🫙 Storage: Keep refrigerated for up to 1 week, or freeze in small jars for up to 2 months.