Put the stock for the borscht in a pot, add the smoked ribs, peeled and chopped soup vegetables, dry spices, marjoram and dried boletus and pour over cold water. Once the stock begins to boil, reduce the heat and cook for about 2 hours. Then strain the stock, leaving only the liquid (optionally leave the meat from the smoked ribs).
Cut the sausage into 1 cm cubes, fry on a pan together with the white onions and frozen boletus, when the sausage is browned, add everything to the pot with stock and cook for about 30 minutes.
Add the borscht sourdough starter, sliced potatoes and 36% double cream to the pot, cook for about 30 minutes until the potatoes are tender and the borscht is slightly thickened and season to taste with salt and pepper. Add a boiled egg and a leaf of baby lettuce to the portion of borscht on the plate. Enjoy!