In a sauce pan on medium heat add Oil, allow to get hot. Add Onion, lightly season with Salt, Pepper, and Garlic Plus. Saute for 15 minutes, stirring frequently. Add Sausage, sauté for 5 minutes, while breaking up. Make a well in centre of the pan, add Garlic, sauté 15 seconds. Deglaze pan with Wine, allow Wine to mostly reduce.
Add Flour, stir into Onion mixture, until all white from Flour is gone. Add Salt, Pepper, Mustard, Worcestershire, and Chicken Stock, stir to mix well. Bring to a simmer, cover, simmer for 15 minutes.