Spicy Vegetable Soup

Heat oil in a Dutch oven over medium heat. Add onion, cover and cook, stirring occasionally, until beginning to brown, about 6 minutes. Add paprika and cook, stirring, for 30 seconds. Add broth, tomatoes, squash, potatoes and beans; bring to a boil. Reduce heat to a simmer and cook, stirring occasionally, until the vegetables are just tender, about 12 minutes. Stir in spinach and vinegar; continue cooking until heated through, 2 to 4 minutes more. Ladle soup into bowls and top with fresh basil or a dollop of pesto.