This soup comes in a number of versions, but the essential ingredients are buttermilk or yogurt, dill and cucumbers. We like it with raisins (soaked for half an hour before mixing).
I've seen recipes for it with walnuts, onions, white pepper, added salt, tomatoes and I'm sure many other possibilities.
Blend the ingredients together well in a food processor. Taste and adjust whatever seems to be missing -- cucumbers seem to be the biggest variable in our experience -- I peel them, but use the seeds and pith which have more flavor and which mix well with the rest of the ingredients.
The soup is better after a day or even two in the fridge where the flavors meld together in quite an extraordinary way.
Serve very cold, perhaps with shaved ice. Mix well before serving to get the raisin bits into suspension, if you use raisins.
Regards, Bob