1. Preheat your oven to 350°F. Put the kielbasa in a 2-quart baking dish, and bake until browned (about 5 minutes). Drain the fat and set the dish aside.
2. In a nonstick skillet over medium-high heat, cook the onion, mushrooms, and garlic for 5 to 7 minutes. Transfer to the baking dish, then add the beans and tomatoes, plus salt and pepper to taste.
3. Bake for 20 minutes or until the edges bubble.
4. In a small bowl, mix the bread crumbs and flaxseed with the oil. Sprinkle over the sausage mixture, and broil 4 to 5 inches from the heat until the top is golden (about 3 minutes).