Steam the finely chopped onion in sunflower oil until translucent. Then pour in the vegetable stock, add the peas and let simmer covered for about 5 minutes.
Put the cornstarch in a bowl and stir with water until smooth. Add to the broth together with the cream and creme fraiche and bring to the boil while stirring. Puree the pea soup in a blender and season with salt, pepper and nutmeg to taste.