Sweat the onions in a little clarified butter until translucent. Add the garlic and sweat a little more. Deglaze with white wine and add the veal stock and cream. Bring to the boil and reduce by about 1/5 over low to medium heat. Season to taste with salt and pepper. Remove from heat and let cool down to a maximum of 50 ° C. Finely puree in a blender together with the sorrel.
If the soup base is to be prepared a little earlier, add about 1/3 heaped teaspoon lecithin (or an egg yolk) when mixing to prevent the soup from separating.
Gently fry the snails in a little clarified butter without roasting them. Pour in the soup and let it warm up briefly - never bring it to the boil again (if egg yolk was used, do not exceed 80 ° C).