25 mins. 1  Preheat oven to 400Â°. 2  In skillet, cook onions in 2 tablespoons oil over medium heat, stirring occasionally until golden. 3  Add flour and cook for 2 minutes, stirring to combine.  Stir in wine, tomato paste, broth and 1  gravy. Simmer sauce, stirring 3-5 minutes.  Stir in mustard.