Calf lungs in sour sauce

We rinse the lungs thoroughly, remove the trachea. It is advisable to soak the lungs for several hours. Add light, salt, pepper, spices to boiling water. If desired, you can add a whole onion, roots. Cook under the lid for about
1. 5 hours. In 15-20 minutes, add a bay leaf. Filter the broth. For the sauce in heated oil, fry the onion, cut into cubes, add flour, dilute everything with cold broth, salt. After that, pour vinegar or diluted citric acid to taste, add sugar, sour cream or ground yolk, mix thoroughly. Cut the cooked lungs into strips, put them in a sauce and let them boil. We serve lungs with mashed potatoes, salad from canned vegetables, etc.