Alison's Lunch

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black bean soup with sweet potatoes

black bean soup with sweet potatoes

I made this soup based on recipe by Lori Longbotham, in an email from Fine Cooking. But instead of just cooking the sweet potatoes in the soup, as she recommends, I roasted slices of sweet potatoes and added them as a garnish at the end. Also I used home-cooked black beans instead of canned ones, so I didn’t have to use stock, as her recipe called for. But you could substitute canned beans and stock if you like, instead of cooking your own beans and using the bean cooking liquid. 

As Ms. Longbotham pointed out in her recipe, “The sweet potatoes in this soup contrast nicely with the tang of the yogurt and the tartness of the lime. Aniseed lends an unusual hint of licorice flavor.”

If you have time, cook the beans and make the soup ahead of time, like the day before, and then roast the sweet potatoes just before dinner. Or you can roast the sweet potatoes ahead, too, and just reheat everything when you’re ready to eat. This soup freezes wonderfully, too.

Oh, and one more thing—about the sweet potatoes. First, let’s make sure we’re talking about the right vegetable. Sweet potatoes like the ones I’ve used in this recipe are usually called yams in the grocery store—for example, garnet yams. Use the really orange ones.

The Beans

4 cups black beans, soaked for 4 hours or overnight
1 onion, peeled and quartered
4 garlic cloves, peeled but left whole
kosher salt or sea salt

Drain the soaked beans, rinse them, and then put them in a large pot and cover with cold water by a couple of inches. Add the quartered onion and garlic and make sure the water covers the onions. Bring to a boil, then lower the heat and simmer, partially covered, until the beans are tender. This could take 45 minutes to 1 ½ hours, depending on the size of the beans and how old they are. When the beans are tender enough to easily squish between your tongue and the roof of your mouth, turn the heat off. If you have time, let the beans sit in their liquid with the aromatics until cool. Remove the quartered onions and whole garlic and discard. Add salt to the beans to taste.

The Soup

1 to 2 tablespoons olive oil
2 yellow onions, chopped
6 medium cloves garlic, minced
1 tablespoon ground coriander
2 teaspoons ground cumin
¼ teaspoon aniseed
Freshly-ground black pepper
kosher salt or sea salt

Warm the olive oil in a large, heavy soup pot. Add the onion and cook over medium heat until the onion is soft and golden brown, 8 to 12 minutes. Add the garlic, coriander, cumin, aniseed, and ¼ teaspoon pepper and cook, stirring constantly, until fragrant, about 30 seconds. Add the beans and broth and bring to a boil over high heat. Reduce the heat and simmer, uncovered, stirring occasionally, for 15 or 20 minutes. Taste the soup and add salt I f needed, stir well, and set aside until an hour and a half before dinnertime.

While you’re roasting the sweet potatoes, and/or when the soup is cool enough to handle without burning yourself, using a slotted spoon, set aside 2 or 3 cups of the beans and onions. Puree the remaining soup in batches in a blender. Return the solids to the soup, and when you’re ready to eat, reheat over gentle heat, stirring often (Don’t burn the beans!) and season to taste with salt, pepper and a little lime juice.

The Sweet Potatoes

4 medium sweet potatoes (called yams at the grocery store—get Garnet Yams, or something similar), peeled and sliced into ¾-inch thick rounds
2 tablespoons olive oil
1 teaspoon sea salt or kosher salt

My method for roasting these is from Cook’s Illustrated. The reason for all the shenanigans with the foil at the beginning is that starting the sweet potatoes in a cold oven keeps the temperature lower at first, to allow more of the starches in the sweet potatoes to convert to sugars. Then the 425-degree final temperature browns and caramelizes them. If you prefer not to peel the potatoes, just scrub them well before cutting.

1. Toss sweet potatoes in large bowl with oil and salt until evenly coated. Grease one or two large rimmed baking sheets with olive oil or cooking spray.
2. Arrange sweet potatoes in single layer on baking sheet(s) and cover tightly with aluminum foil. Adjust oven rack to middle position and place yams in COLD OVEN. Turn oven on to 425 degrees and cook sweet potatoes 20 to 30 minutes, until they are starting to get tender.
3. Carefully remove foil, and return sweet potatoes to oven and cook until bottom edges of yams are golden brown, 15 to 25 minutes. If they are very tender and brown, they are already done! (Whether they are done or not will depend on how fast your oven heats up.) If not tender yet, go to Step 4.
4. Use a spatula to flip slices over. Continue to roast until bottom edges of sweet potatoes are golden brown, and they are quite soft in the center, 10 to 20 minutes longer.
5. Remove from oven; let them cool for a bit, and then cut some of them into small pieces to sprinkle on top of your soup.

The Other Garnishes
½ cup plain yogurt, salted to your taste (optional—I actually liked it better without the yogurt)
fresh lime juice, or wedges or slices of lime

Serve each bowl of soup topped with sweet potato cubes and, if desired, a dollop of yogurt, and a squeeze more lime juice if it needs it.