This soup is a beauty, and wins big points for versatility! I adore this soup chilled in the summer; it is smooth, creamy, earthy and cool. The crema provides random pockets of mild heat, and the Pepita's salty crunch punctuates it's velvety lusciousness. It's an awesome first course or lunch main dish, and when cold weather returns, it is equally amazing as a hot soup! This is a recipe for all seasons, and a must-make. A lovely side benefit are the basic, healthy ingredients in the recipe. I discovered this unique cooking technique for sweet potatoes last year; don't deviate from it! It's soaking the sweet potatoes and skins in the hot liquid that creates the silky texture in the finished product. Serves 4 as a main course or 6 as a first course.
4 Tablespoons unsalted butter
1 shallot, thinly sliced
4 sprigs fresh thyme
1/2 teaspoon dried coriander
4 1/4 cups water
2 pounds sweet potatoes, peeled, halved lengthwise, and sliced 1/4-inch thick, plus reserved 1/4 of the peels
1 Tablespoon packed brown sugar
1/2 teaspoon cider vinegar
Salt & Pepper
*Sweet & Spicy Crema (can be prepared while potatoes and skins stand in the water)
1/2 cup Greek yogurt
1 tablespoon fresh lime juice
1/8 teaspoon cayenne pepper
1/8 teaspoon chipotle pepper powder
pinch of salt
2 teaspoons maple syrup
2 tablespoons half-and-half or whole milk
Roasted, salted pepitas for garnish
Melt the butter in a large saucepan over medium-low heat. Add the shallot, thyme, and coriander and cook until the shallots are soft but not browned, about 5 minutes. Add the water, increase the heat to high, and bring to a boil. Remove the pot from the heat, add the sweet potatoes and reserved peels, and let stand for 20 minutes. (This is a good time to make the crema, especially if the soup will be served hot.)
Add the brown sugar, vinegar, 1 1/2 teaspoons salt, and 1/4 teaspoon black pepper to the potatoes and skins. Bring to a simmer over high heat. Reduce heat to medium-low, cover, and cook until the potatoes are very soft, 10-15 minutes.
For Chilled Soup: While the potatoes finish cooking, prepare an ice bath in the sink or in a dish pan. Remove the potatoes from the heat and pour into a large stainless bowl. Place the bowl in the ice bath. Stir occasionally until the mixture is cool. Remove, dry the bowl, cover, and refrigerate until very cold. Once chilled, process in batches in the blender until totally smooth. Serve immediately or refrigerate until ready to serve.
For Hot Soup: When the potatoes are soft, use an immersion blender to blend the potato mixture in the pan until silky smooth. Serve immediately. Store cooled leftovers in the refrigerator for up to 3 days.
*To make the Crema: Whisk all together in a bowl until thoroughly combined. Place in a squeeze bottle and refrigerate until ready to serve. Alternately, place in a bowl with a lid and refrigerate; use a spoon to swirl it over the soup instead of squeezing it out of a bottle.
To Serve (either version): Place soup in serving bowl. Swirl the crema (about 2 Tablespoons) over the top of the soup, then sprinkle with the pepitas.