Soak the oat grains in a little water for 4 to 6 hours.
Boil the water with the stock cubes and season with salt. Drain the oat grains and cook them in the vegetable soup for 40 to 60 minutes.
In the meantime, clean and rinse the cauliflower and cut it into small roses. Rinse the carrots, remove the peel and cut into slices. Remove the peel from the kohlrabi and cut into cubes. Clean and rinse the leeks and onions and cut them into rings. Remove the pods from the fresh peas. Melt the butter in a saucepan and lightly sweat the turmeric and flour in it.
Add the whipping cream and simmer everything together without a lid for about 15 minutes on low heat.
In the meantime, add the vegetables to the clear soup and simmer for 10 minutes. Add the turmeric cream just before serving.