Set your oven to 350°F (175°C). Lightly grease a medium baking dish.
Heat a large skillet over medium. If your sausage is very lean, add 1 teaspoon olive oil. Brown the sliced sausage for 3–4 minutes per side until caramelized. Transfer to a bowl.
In the same pan, add onions and a pinch of salt. Cook 4–5 minutes until translucent and lightly browned. Stir in garlic for 30 seconds until fragrant (aka don't burn it).
Add tomato sauce, tomato paste, maple syrup, vinegar, Dijon, smoked paprika, cumin, black pepper, and broth. Stir to combine. Simmer 3–4 minutes until slightly thickened. Taste; adjust salt, vinegar, or maple as needed.
Stir in the rinsed beans and the browned sausage. Add liquid smoke if using. Mix gently so you don't break the beans. The mixture should be saucy but not watery.
Transfer to the baking dish. Bake uncovered for 25–30 minutes until bubbling and glossy with light caramelization around the edges.
Let it sit 10 minutes so the sauce thickens. Garnish with parsley or scallions if you're feeling fancy.