Form the sausage into eight 1/2-inch-thick patties.
Heat 1 tablespoon of the oil in a medium skillet over medium heat. Add the peppers, shallots and garlic and cook, stirring occasionally, until soft, about 8 minutes. Add the tomato sauce and simmer until slightly thickened, about 3 minutes.
Meanwhile, heat a large nonstick skillet over medium-high heat. Add the sausage patties and cook, turning once, until golden brown on both sides and cooked through, about 4 minutes per side.
Place the patties onto the bottom buns and top with some of the pepper mixture and a sprinkling of parsley. Top with the top buns and serve immediately.