Peel and roughly dice the onion. Wash the cucumbers, cut off the ends. Peel and halve the cucumbers and remove the seeds with a tablespoon. Clean, wash and thinly slice the carrots. Wash the meat, dab dry with kitchen paper and dice.
Put rice in 400 ml boiling salted water, bring to the boil again. Cover and let it swell at low heat for about 20 minutes. Heat oil in a frying pan and fry meat while turning. Remove from the pan and set aside. Add the cucumbers and onions to the pan and fry while turning. Add carrots and meat, season with salt and pepper. Deglaze with stock and cream, bring to the boil, cover and simmer over medium heat for about 15 minutes. In the meantime wash dill, dab dry and chop. Stir in horseradish and 3/4 of the dill. Season to taste with salt, pepper, lemon juice and sugar.
Deglaze with stock and cream, bring to the boil, cover and simmer over medium heat for about 15 minutes. In the meantime wash dill, dab dry and chop. Stir in horseradish and 3/4 of the dill. Season to taste with salt, pepper, lemon juice and sugar. Bring to the boil, stir in sauce thickener and bring to the boil again. Serve with the remaining dill and garnish with dill flags and lemon wedge if desired. Serve with rice