Use this recipe when making our Almond Custard Cake.
Bring rhubarb, sugar, and 1/4 cup water to a simmer in a medium saucepan over medium-high heat, stirring occasionally. Cook until liquid is reduced by half, about 8 minutes. Stir in strawberries and vanilla; cook until berries are softened, about 3 minutes more. Serve the sauce warm or at room temperature.
This sauce can be made two days ahead and refrigerated in an airtight container. Reheat over medium-low heat or bring to room temperature before serving.