Peel the rhubarb, do not boil, and cut into pieces approx. 2 cm in size. Knead all other ingredients well in a bowl. The consistency should be such that you can press the dough firmly, but also crumble it.
Line a baking dish with the batter. Spread the dough around the edges and press on. Leave some batter for the crumble. Put the rhubarb pieces in the baking dish. Spread the rest of the dough on top as a crumble. Bake the crumble for approx. 20 - 30 minutes at a medium temperature (approx. 175 ° C).
The rhubarb crumble tastes great with vanilla sauce, cold or warm.
Warning: margarine often contains whey products. Vegan are e.g., Alsan or Sojola and mostly sunflower margarine.