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1
Preheat an oven to 425 degrees F. Mix sweet potatoes, onions, thyme and sage in large bowl.
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2
Drizzle with olive oil and salt, and toss to coat.
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3
Spoon mixture onto a baking sheet, spreading vegetables out in a single layer.
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4
Place baking sheet in oven and roast until vegetables are caramelized, stirring occasionally, about 25 minutes.
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5
Remove vegetables from oven and process in a blender until pureed.
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6
Slowly add chicken broth and process until smooth.
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7
Pour soup into a large saucepan and add chiles, lime juice, sugar, nutmeg and pepper.
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8
Bring soup to a boil, reduce to a simmer and cook for 15 minutes.
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9
Remove and discard the whole chipotle chiles, stir in cream and adjust seasonings.
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10
Ladle into soup bowls and garnish with green onion, fried sweet potato chips and crema.
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11
Make the sweet potato chips: Peel sweet potato.
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12
Using a mandoline or food processor fitted with the 2 millimeter slicing blade, cut into 1/1-6 inch slices, lengthwise.
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13
Heat oil in a large stock pot or saucepan to deep-fry temperature (350 degrees F).
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14
Fry sweet potatoes, a handful at a time, until pale golden and crisp.
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15
Remove with a slotted spoon, drain on paper towels, and sprinkle with salt.
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16
Reserve a day or two in plastic bags.
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17
For the crema: Whisk the cream and buttermilk together.
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18
Cover and set in a warm place (a gas oven with just the heat from the pilot is fine) for 8 hours.
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19
Crema may be kept in the refrigerator as long as a week.
