Combine the rhubarb, raspberries, sugar, and flour in a saucepan and cook over medium heat until the juices thicken, about 5 to 7 minutes. Reduce the heat and simmer for 20 to 30 minutes, until the rhubarb is soft. Transfer to a 4-cup shallow ovenproof baking dish and set aside.
Preheat the oven to 475 degrees. Make the meringue.
Fill a clean pastry bag fitted with the giant open star tip with the meringue. Pipe out the meringue onto the raspberry mixture into a simple latticework topping. Bake until very lightly browned, about 5 to 7 minutes. Serve immediately.
Would like to use frozen raspberries in this recipe and wondering if they will work and if the amount of sugar should be adjusted?
Strawberries, in season, worked wonderfully in place of raspberries and a lot more economical.