Wash zucchinis, cut into halves, core and chop. Salt and set aside. Mix minced meat with chopped onion, egg, pepper, salt and knead well. Heat the oil an a saucepan, sauté the remaining chopped onion and zucchini pulp, add the flour, stir and pour the broth. Boil the sauce for 2-3 minutes, stirring occasionaly, add the sour cream. Fill zucchinis with minced meat, place in the baking form, pour the sauce and bake at 200 degrees Celsius for 20-30 minutes.