Preheat the oven to 350 degrees. Heat the oil in a large, oven safe skillet. Add in the ground beef and chopped onion. Pour 1/4 cup red wine over meat and brown. Add in the mixed vegetables and allow to simmer over med low heat for five minutes. Add mashed potatoes over the top and place skillet in the oven. Heat for 15-20 minutes then add cheese and bake for an extra 5 minutes.