Trim the sorrel, wash a few times in cold water and drain well. Check that no sand remains on the leaves. Peel and finely chop the onions. In a 3 quart pot heat the oil, sauté the onions over medium heat for 2-3 minutes. (If you prefer it without the onion, leave it out.) Add the sorrel and steam for 10 minutes until it is very soft and the liquid evaporates. Thicken by sprinkling the flour on the sorrel. Cook and stir for 1 minute, taking care not to burn the flour. Add the milk and the water, bring to a boil and beat for 3-4 minutes while it thickens. Add some salt, sugar and finally
the sour cream. To prepare a sauce, mix in a blender until completely smooth.
Preparation time: 45 minutes
One serving: 1100 kJ/263 kcal