Sour sauce
For the sauce, fry onions cut into cubes with heated fat, add flour, dilute everything with cold broth, salt. After that, pour vinegar or diluted citric acid to taste, add sugar, add sour cream or ground yolk and mix thoroughly.
flour - 40 g, sour cream - 0.5 cups, or yolk - 1 pc., onions - 0.5 pcs., bay leaf to taste, vinegar to taste, sugar to taste, salt to taste