Heat all ingredients in a medium saucepan over medium-high heat. Cook until strawberries and rhubarb begin to release juices and soften, 15 to 20 minutes.
Remove the saucepan from heat, and using a potato masher or back of a large spoon, mash the fruit to create a smooth sauce while still keeping some texture.
Let the sauce cool completely before serving a spoonful on top of homemade yogurt. (Warm Strawberry Rhubarb Sauce would also be delicious on ice cream!)
Store in a glass jars with a lid and refrigerate for 2 weeks.
