1: Beef fillet is what we usually call beef fillet.

The steak is a piece of meat above the tenderloin.

The naked eye is the piece of meat connecting the inner ridge and other parts, and there is a piece of oil in the middle of this piece of meat. Hence the name.

If fried well, it must be hard, because Chinese food can't make western food.

Make it 50%, 70% and 80% according to your own taste. Then it won't harden. In the process of frying, you can cut a little bit from the corner of the meat with a knife, and watch the change of the internal heating of the meat to master the cooking time and technique to avoid hardening.