Sprinkle the flour over the meat and coat well. Heat half of both the butter and oil in a frying pan. As soon as the butter foams, add the meat and brown it very quickly on all sides. Set aside on a plate.
Add the rest of the butter and oil to the pan and sauté the onion, garlic and sage for a few minutes, then add the mushrooms. Stir well and when the mushrooms start to soften, continue cooking for about 5 minutes longer.
Add the wine to deglaze the bottom of the pan, using a wooden spoon to scrape away any crust that has formed. Add the veal and cook, stirring, until the wine has evaporated. Turn the heat down to low and cook for another 10 minutes.
Season with salt and pepper, and at the last moment, add the cream, let it bubble for 2 minutes, then remove from the heat and serve.