Clean, wash and cut the rhubarb into pieces. Wash, clean and chop the strawberries. Put the rhubarb and strawberries into a greased flat casserole dish (approx. 2 l capacity) and mix with 4 tbsp. sugar.
Preheat oven (electric cooker: 175°C/circulating air: 150°C/gas: level 2). Beat the eggs and 100 g sugar with the whisks of the mixer until creamy. Mix flour, starch and baking powder and stir alternately with buttermilk and oil into the egg mixture.
Pour the dough into the casserole dish. Bake in a hot oven for about 50 minutes. If necessary, cover with aluminium foil after approx. 30 minutes so that the cobbler does not get too dark.
Dust strawberry-rhubarb cobbler with icing sugar and arrange with 1 scoop of vanilla ice cream as desired.