Sweet Potato Soup

By KDHarmon

To highlight the earthiness of the sweet potatoes, we incorporate a quarter of the skins into the soup. In addition to the chives, serve the soup with one of our suggested garnishes (recipes follow). The garnish can be prepared during step 1 while the sweet potatoes stand in the water.

Ingredients

• 4 4 4 tablespoons unsalted butter
• 1 1 1 shallot, sliced thin
• 4 4 4 sprigs fresh thyme
• 4-1/4 4-1/4 4-1/4 cups water
• 2 2 1/4 1/4 sweet potatoes, peeled, halved lengthwise, and sliced 1/4 inch thick, 1/4 of peels reserved
• 1 1 1 tablespoon packed brown sugar
• 1/2 1/2 1/2 teaspoon cider vinegar
• Salt and pepper
• Minced fresh chives

Details

Servings 4
Adapted from cooksillustrated.com

Preparation

Step 1

1. Melt butter in large saucepan over medium-low heat. Add shallot and thyme and cook until shallot is softened but not browned, about 5 minutes. Add water, increase heat to high, and bring to simmer. Remove pot from heat, add sweet potatoes and reserved peels, and let stand uncovered for 20 minutes.

2. Add sugar, vinegar, 1 1/2 teaspoons salt, and 1/4 teaspoon pepper. Bring to simmer over high heat. Reduce heat to medium-low, cover, and cook until potatoes are very soft, about 10 minutes.

3. Discard thyme sprigs. Working in batches, process soup in blender until smooth, 45 to 60 seconds. Return soup to clean pot. Bring to simmer over medium heat, adjusting consistency if desired. Season with salt and pepper to taste. Serve, topping each portion with sprinkle of chives.


Putting Peels to Work:
Instead of discarding the potato peels, we blend some of them into our soup to take advantage of an earthy-tasting compound they contain. The compound, called methoxypyrazine, is potent—it’s detectable in water in levels as low as one part per trillion—so we use only one-quarter of the peels in order to avoid overwhelming the soup.





Instructions
Serves 4 to 6 as a main dish or 8 as a starter



To highlight the earthiness of the sweet potatoes, we incorporate a quarter of the skins into the soup. In addition to the chives, serve the soup with one of our suggested garnishes (recipes follow). The garnish can be prepared during step 1 while the sweet potatoes stand in the water.



1. Melt butter in large saucepan over medium-low heat. Add shallot and thyme and cook until shallot is softened but not browned, about 5 minutes. Add water, increase heat to high, and bring to simmer. Remove pot from heat, add sweet potatoes and reserved peels, and let stand uncovered for 20 minutes.

2. Add sugar, vinegar, 1 1/2 teaspoons salt, and 1/4 teaspoon pepper. Bring to simmer over high heat. Reduce heat to medium-low, cover, and cook until potatoes are very soft, about 10 minutes.

3. Discard thyme sprigs. Working in batches, process soup in blender until smooth, 45 to 60 seconds. Return soup to clean pot. Bring to simmer over medium heat, adjusting consistency if desired. Season with salt and pepper to taste. Serve, topping each portion with sprinkle of chives.

Makes 4-6 main course servings, 8 as a starter.



Putting Peels to Work:
Instead of discarding the potato peels, we blend some of them into our soup to take advantage of an earthy-tasting compound they contain. The compound, called methoxypyrazine, is potent—it’s detectable in water in levels as low as one part per trillion—so we use only one-quarter of the peels in order to avoid overwhelming the soup.

Thinning Sweet Potatoes with Less Liquid:
Creating a soup with prominent sweet potato flavor meant using a minimal amount of water. The only catch? Sweet potatoes require more water than less starchy vegetables like squash or carrots to be thinned to a soupy consistency after boiling. That’s because their large starch molecules form a loose mesh that traps added water, preventing the texture from turning runny. Eventually, if enough water is added, the mesh can’t hold any more liquid, and the texture loosens and thins.

But we discovered a trick: By adding the sweet potatoes to simmering water and then letting them sit off heat for 20 minutes before boiling them, the large starch molecules are converted into much smaller sugar molecules that are unable to create a mesh. This meant that we only needed to puree the sweet potatoes with the 4 1/4 cups of cooking liquid to get just the right consistency, with no additional liquid needed. But that’s not the only benefit: The conversion of starch to sugar also makes the potatoes taste even better.