Sauerbraten, marinated in buttermilk

Ingredients for 4 servings:

• 1 kg beef
• 1 liter buttermilk
• 1 onion(s), sliced
• 2 bay leaves
• some pepper, whole grains
• Mustard
• 2 onions, roughly chopped
• 2 tomatoes, roughly chopped
• 1 stalk(s) Celery, roughly chopped
• 1 piece(s) of brown bread (sliced, crisped, sliced)
• 1 cup sour cream
• salt and pepper

Instructions

Working time approx. 30 minutes; Rest period approx. 2 days; Total time approx. 2 days 30 minutes

Pour buttermilk over the meat, ensuring it is covered. Add the onions, bay leaves, and peppercorns. Let it simmer in a cool place for about 2 days, turning occasionally. Pat dry before roasting, rub with mustard, salt, and pepper. Brown, add the vegetables, then the bread. Pour in water, cover, and simmer. Add more water if necessary. Finally, add enough to make a good gravy. Remove the roast and let it rest, covered, in a warm oven. Depending on your taste, you can leave the vegetables in the sauce and purée them, or strain them. Season the sauce with salt, pepper, and sour cream, bring back to a very high heat, and serve with the roast, which has been cut into neat slices.