In a heavy saucepan, heat the butter and bacon fat until foaming. Add diced onion and shallots; cook and stir for 5 minutes. Toss garlic, thyme and 1 â&dbquo;2 tsps. salt into the pan, and cook 5 minutes longer. Add carrots and potatoes; cook and stir for 5 minutes. Add chopped tomatoes, white wine