Bring to a boil, reduce heat, and cook for 2 hours. Meanwhile, prepare the rest of the vegetables and set aside. Place the parsnips in a small amount of water in a small saucepan. Cook until soft, about 15 minutes. Cool. Place in a blender or food processor and process until smooth. When beans are almost tender, add the pureed parsnips and the carrots and zucchini. Cook for 30 minutes, then add the pasta and bulgur. Cook an additional 15 minutes. Stir in the lemon juice and spinach and cook about 5 minutes. Serve at once.