Vegetable Soup with Kielbasa

1 onion, chopped (1 cup)
8 oz. kielbasa, 1/4 inch pieces
2 cans of tomato soup
1 can cannellini beans (15.5 oz)
1 package frozen mixed vegetables, thawed
1 package frozen spinach, thawed

In a large pot, heat 1 tablespoon oil over medium heat. Add onion and kielbasa; cook, stirring until browned 10 minutes. Stir in soup, 2 cups water and beans; bring to a boil. Reduce heat to medium-low, cover and cook 10 minutes. Stir in mixed vegetables, spinach and 1/4 teaspoon pepper. Cover, cook until heated through 10 minutes adding additional water if soup is too thick.