Step 1 Clean rhubarb stalks, removing leaves and trimming ends. Cut into 1-inch chunks. Combine rhubarb and sugar in large saucepan. Stir in water. Heat to simmering. Simmer until rhubarb is tender, about 3 minutes. Stir in raspberries and simmer 1 minute more. Pour into serving bowl and cool. Cover and refrigerate several hours or overnight before serving.