Steamed sauce
Put the chopped onions, parsley or celery in the finished white sauce and cook for 30 minutes. Then add white grape dry wine, citric acid or lemon juice, ground pepper, salt and bring to a boil. Put the butter pieces, stir until fully combined with the sauce and strain.
onions - 1 pc., parsley root - 1 pc., or celery root - 1 pc., citric acid - 1.5 tsp, white table wine - 0.25 cups, butter - 2 tbsp. spoons, pepper to taste, salt to taste