The strawberries are washed, mashed and set aside. The rhubarb is cleaned and washed (do not peel off), then cut into pieces approx. 2 cm long and cooked with a little water for approx. 10-15 minutes. Add the strawberry purée and the butter-vanilla baking flavor. With a packet of preserving sugar 1: 1 you cook the jam as described in the instructions. Pour boiling hot into glasses and enjoy.