Portuguese Bean Soup with Sweet Potatoes

I love soups even in warmer weather. 

Portuguese Bean Soup with Sweet Potatoes

 2 teaspoons olive oil
 1 cup coarsely chopped white onion
 3 cups reduced-sodium chicken broth
 1 cup diced (one-half inch pieces) unpeeled sweet potato
 3 to 4 teaspoons chili garlic sauce or chili puree with  garlic, such as Lee Kum Kee brand
 1 can (14. 5 ounces) diced tomatoes, undrained
 One 15- or 16-ounce can Great Northern or cannelloni beans,  undrained
 4 cups packed sliced Swiss chard or collard greens
 4 teaspoons balsamic vinegar (optional)

Heat a large saucepan over medium-high heat. Add oil, then onion; cook three minutes, stirring occasionally. Add broth, sweet potato, and chili garlic sauce; bring to a boil over high heat. Reduce heat; simmer uncovered five minutes. Stir in tomatoes and beans; return to a simmer. Stir in Swiss chard or collard greens. Simmer five minutes or until sweet potatoes and chard or greens are tender. Stir in vinegar, if desired, and ladle into four serving bowls.

Substitutions
Diced, peeled butternut or delicate squash may be substituted for the sweet potato. Kale, turnip, or beet greens may replace the Swiss chard or collard greens.

Total fat (g): 3.7;Fat calories (kc): 33.3;Cholesterol (mg): 2.4;Saturated fat (g):0. 8;Polyunsaturated fat (g):0. 3;Monounsaturated fat (g): 2.1;Fiber (g): 8.2;Carbohydrates (g): 30;Sugar (g): 7.3;Protein (g): 9.9;Sodium (mg):