Preheat oven to 175°C (350°F).
Onion fondue: put onion and white wine in a casserole and cook over low heat until wine has completely evaporated, about 20 minutes. Add cream and reduce. Season with salt and pepper to taste. Set aside.
Sauce, heat olive oil in skillet, add shallots and lightly simmer until soft and translucent. Add red wine and reduce by two-thirds. Add demi-glace sauce and bring to boil. Add peppers, oregano and garlic and simmer for a few minutes.
Heat butter in skillet and sauté veal medallions for about 2 minutes on each side, transfer to oven for 5 minutes or just until a thermometer registers 60°C (140°F), making sure that the meat is still pink in the middle.
To serve, divide onion fondue onto 4 plates, top with veal medallion and dress with sauce.Serve with a side of Brussels sprouts sautéed with bacon cubes and steamed small new potatoes.