In a large Dutch oven or heavy‑bottom stock pot, heat the oil over medium‑high heat. Add the sliced sausage and cook for about 5 minutes, stirring occasionally, until browned.

Add the chopped onion, green bell pepper, carrot, and minced garlic. Season with the kosher salt and black pepper. Cook, stirring occasionally, until the onion and pepper soften, about another 5 minutes.

Sprinkle the flour over the sausage‑and‑veggie mixture and stir to coat evenly. Continue cooking for about 1–2 minutes, stirring, until the raw flour taste is gone and it begins to smell toasty.

Slowly pour in the milk while stirring so the flour mixture (roux) combines smoothly and without lumps. Raise the heat enough so the mixture begins to thicken and bubble gently, stirring frequently to prevent burning.

Once thickened, add the Worcestershire sauce, ground sage, and both the white beans and kidney beans (rinsed and drained). Stir to combine, then reduce the heat to medium‑low.

Let the soup simmer, uncovered, for 15–20 minutes, stirring occasionally, until the flavors meld and the texture is creamy and cohesive. Taste and adjust seasoning with additional salt and pepper as desired.

Serve the soup hot, garnished with chopped parsley. Accompany with slices of crusty French bread or a handful of crackers for dipping.