Clean, wash and cut the rhubarb into small pieces. Put rhubarb and sugar in a pot. Let it stand for about 30 minutes until juice is produced. Wash, clean and halve or quarter the strawberries. Add lemon zest and 75 ml water to the rhubarb and steam for 3-4 minutes. Cook on low heat for 3-4 minutes.
Stir starch and some cold water until smooth. Bring the rhubarb to the boil, stir in the mixed starch. Bring to the boil again briefly. Fold in strawberries. Let the compote cool down. Remove lemon peel. Cream butter, sugar and vanilla sugar. Stir in eggs one after the other. Stir in flour and vanilla flavouring. Add buttermilk and stir in. Preheat waffle iron. Coat with some oil.
Stir in eggs one after the other. Stir in flour and vanilla flavouring. Add buttermilk and stir in. Preheat waffle iron. Coat with some oil. Bake about 10 waffles of the dough one after the other until golden brown. Serve the waffles with compote and vanilla ice cream. Dust with icing sugar