For the crumble, melt 40 g butter and crumble into crumbles with nuts, flour, 50 g sugar, oat flakes and salt. Peel the rhubarb and cut into 2 cm long pieces, sauté in the remaining butter for 2 minutes.
Quarter the strawberries and place in a greased baking dish with the rhubarb, sprinkle with the remaining sugar and the crumble. Bake in the oven at 180 ° C for about 15 minutes and serve lukewarm.