Rognone di manzo in umido

• 2 beef kidneys, about 1½ pounds (700 g) total
• scant

Soak the kidneys in the vinegar and enough water to cover for 10 minutes. Drain and slice the kidneys. Put the slices in a skillet and sauté over a lively flame for about 2 minutes, or until the liquid that they throw off evaporates. When the pan is perfectly dry, set aside and keep warm.

Chop the parsley leaves. Chop the onion and put it in a pan with the lard. Cook over medium heat fo