Black Bean Soup

brought by Heather Brown

recipe adapted from Cook's Illustrated

Makes About 9 Cups

Dried beans tend to cook unevenly, so be sure to taste several beans to determine their doneness in step 1. For efficiency, you can prepare the soup ingredients while the beans simmer and the garnishes while the soup simmers. Though you do not need to offer all of the garnishes listed below, do choose at least a couple; garnishes are essential for this soup as they add not only flavor but texture and color as well. Leftover soup can be refrigerated in an airtight container for 3 or 4 days; reheat it in a saucepan over medium heat until hot, stirring in additional chicken broth if it has thickened beyond your liking.

Beans
1	pound dried black beans (2 cups), rinsed and picked over
5	ounces ham steak , trimmed of rind (about 3/4 of a small ham steak)
2	bay leaves
5	cups water
1/8	teaspoon baking soda
1	teaspoon table salt
Soup
3	tablespoons olive oil
2	large onions , chopped fine or processed in food processor
1	large carrot , chopped fine or processed in food processor
3	ribs celery , chopped fine or processed in food processor
1/2	teaspoon table salt
5 - 6	medium cloves garlic , minced
1/2	teaspoon red pepper flakes
1 1/2	tablespoons ground cumin
6	cups low-sodium chicken broth
2	tablespoons cornstarch
2	tablespoon water
2	tablespoons lime juice , from 1 to 2 limes
Garnishes
	lime wedges
	minced fresh cilantro leaves
	red onion , finely diced
	avocado , diced medium
	sour cream (or plain yogurt)

Directions

1. FOR THE BEANS: Place beans, ham, bay, water, and baking soda in large saucepan with  lid. Boil over medium-high heat; remove any foam that rises to the surface. Stir in salt, reduce heat to low, cover, and simmer briskly until beans are tender, 1 1/4 to 1 1/2 hours (if necessary, add another 1 cup water and continue to simmer until beans are tender); do not drain beans. Discard bay leaves. Remove ham steak (ham steak darkens to color of beans), cut into small cubes, and set aside.
2. FOR THE SOUP: Heat oil in large pot; add onions, carrot, celery, and salt and cook, stirring occasionally, until vegetables are soft and lightly browned, 12 to 15 minutes. Reduce heat to medium-low and add garlic, pepper flakes, and cumin; cook, stirring constantly, until fragrant, about 3 minutes. Stir in beans, bean cooking liquid, and chicken broth. Increase heat to medium-high and bring to boil, then reduce heat to low and simmer, uncovered, stirring occasionally, to blend flavors, about 30 minutes.
3. TO FINISH THE SOUP: Ladle 1 1/2 cups beans and 2 cups liquid into food processor or blender, process until smooth, and return to pot. Stir together cornstarch and cold water in small bowl until combined, then gradually stir in the cornstarch mixture into soup; bring to boil over medium-high heat, stirring occasionally, to fully thicken. Off heat, stir in lime juice and reserved ham; ladle soup into bowls and serve immediately, passing garnishes separately.