Roe deer fillet

Preparation:

Preparation: Put the fillet in a baking dish, surround it with grapes, arrange a layer of onions, chopped carrots on top and add a few knobs of butter. During cooking, sprinkle occasionally with a glass of water. Before serving, pass the cooking sauce and legumes through a vegetable mill; then put the sauce on the fire with the egg yolk and the port to bind it. Cut the tenderloin into slices and spread the sauce on top.