It takes only 10 minutes to create a colorful ice cream topping that makes the most of a well-loved just-before-summer combo: sweet strawberries and tart rhubarb.
In a large saucepan, place strawberries, rhubarb, sugar, and 1/4 cup water; bring to a simmer over high heat. Cook, stirring occasionally, until rhubarb begins to break down, 6 to 8 minutes.
Refrigerate until cool, at least 1 hour and up to 1 week. Spoon strawberry-rhubarb sauce over scoops of ice cream; serve with shortbread, if desired.