Okroshka

Method

1. 1Boil the potatoes in their skins for about 25 minutes, until a knife slides in without resistance. Boil the eggs for 10 minutes from the moment the water boils, then cool them in cold water. Simmer the beef in lightly salted water for about 1 hour, up to 1.5 hours for a tougher cut, until a fork goes in easily; or skip this and use 250 g of cooked beef or doctor's sausage, which needs no cooking. Cool everything completely, at least 30 minutes, then peel the potatoes and eggs.
2. 2Dice the potatoes, eggs, beef, cucumbers and radishes into small, even, pea-sized cubes. Finely chop the green onions and dill. For the traditional yolk dressing, set aside the yolks of 2 eggs instead of dicing them (see step 4).
3. 3Combine all the chopped ingredients in a large bowl, cover and chill for at least 1 hour. Do not salt yet: salt draws water out of the cucumbers and radishes, and that water thins the soup.
4. 4Stir the Dijon mustard into the cold kvass. For the traditional version, first mash the 2 reserved yolks with the mustard and a few spoonfuls of kvass into a smooth paste, then whisk in the rest of the kvass.
5. 5Just before serving, pour the cold kvass over the chilled mix a little at a time, about 240 ml per portion and 1.2 litres in all, stirring until you have a soup with the pieces covered by liquid, not a salad. Dress only as much as you will eat now.
6. 6Stir in the salt, wait a couple of minutes and taste; add more a pinch at a time until the soup tastes lively. Keep the bowl in the fridge until you ladle it out.
7. 7Serve ice-cold with 1 tablespoon of sour cream in each bowl and, in hot weather, an ice cube.