In a large skillet over medium-high heat, heat the oil. To the skillet, add sausage and cook for 5 minutes, until cooked through. Transfer sausage to a bowl and set aside. To the same skillet, add onions and garlic to the remaining sausage fat in the skillet; cook until soft.
Next, add in the zucchini and squash and cook until slightly brown. Season with salt and pepper, lemon juice and fennel seeds. Pour the broth and sausage on top and sprinkle with parsley. Reduce heat, cover and simmer for about 10 minutes or until all flavors are well developed.