RUB sugar and vanilla seeds with hands in a 9 x 13-in. baking dish. Add rhubarb and toss to combine. Cover with foil and bake until rhubarb is softened and can be easily pierced with a paring knife, about 35 min.
How to poach rhubarb
Nutrition (per ¼ cup)
Kitchen Tip: Cut thicker stalks in half lengthwise for even cooking.