Tomato Soup Florentine

Name: Tomato Soup Florentine
Ingredients: ½ c. onion, finely chopped; 3 T. olive oil; 4 cloves garlic, finely chopped; 1 pinch red pepper flakes; ¼ c. white wine; 28 oz. whole tomatoes with juice; 2 c. chicken broth; 2 T. dried basil or ¼ c. fresh basil leaves, torn; 2 T. sugar; 2 T. balsamic vinegar; 5 oz. frozen spinach, thawed and dried OR 5 oz. fresh spinach leaves