Portuguese Kale and Potato Soup

This soup is wonderful on a cold, winter night. If you want to make it spicier, add more chili flakes or chili powder.
Ingredients
4 cups water or vegetable broth
1 onion, diced
10 garlic cloves, minced
1 chipotle chili in adobo sauce, seeded and finely chopped, or 1/8 tsp crushed red pepper flakes
2 large or 3 small potatoes (preferably russet), diced
1/2 tsp salt (optional)
4 cups stemmed and finely chopped kale
1 cup crushed tomatoes or tomato sauce
6 ounces vegetarian sausage
PER SERVING: 91 calories; 1.5 g fat; 0.2 g saturated fat; 14.7% calories from fat; 0 mg cholesterol; 5.8 g protein; 15.1 g carbohydrate; 2.1 g sugar; 2.3 g fiber; 260 mg sodium; 62 mg calcium; 1.3 g iron; 23 mg vitamin C; 3077 mcg beta-carotene; 0.7 mg vitamin E
Preparation
Heat 1/2 cup of the water in a large pot. Add the onion, garlic, and chili and cook over high heat, stirring often, for 3 to 5 minutes, or until the onion is soft.
Add the remaining 3 1/2 cups of broth or water, the potatoes, and optional salt. Bring to a simmer, cover, and cook, stirring occasionally, for about 20 minutes, or until the potatoes are tender when pierced with a knife.
Stir in the kale and crushed tomatoes. Cover and cook for about 5 minutes, or until the kale is tender.
Crumble the vegetarian sausage into the soup, stir to mix, and heat until the soup is steaming and the sausage is heated through.
Stored in a covered container in the refrigerator, leftover Portuguese Kale and Potato soup will keep for up to 3 days.