Rinse beans and soak in water to cover for several hours or overnight. Drain, rinse again, and put into a soup pot. Add onions, garlic, and stock. Bring to a boil, reduce heat, and simmer for 1-½ hours, or until beans are cooked through but still retain some texture. Add tomato sauce, kale, and zucchini. Bring to a boil and cook, stirring constantly, for 2 to 3 minutes, depending on how much texture you like. Add cilantro. Taste, then season with salt and pepper.