Secret number one. Minced meat should be absolutely fresh from aged fresh meat. Theoretically. Yesterday the bull was bellowing. Today, minced meat and cutlets.
The secret of the second. The ratio of fats. 80% meat and 20% fat. If you cook from the neck, then 90% lean meat, 10% fat from the back of the carcass.
Cut the meat and lard into cubes with sides of 2 cm, put in the refrigerator and cool well. Pass the minced meat through a large grate. Until the moment of frying, nothing is added to the minced meat: neither salt, nor seasonings, nor onions. Put the filling in the refrigerator for 30 minutes. Remove the meat grinder to the cold.