How to Make It
Heat oil in a Dutch oven over medium. Add shallots, lemongrass, ginger, and garlic; cook, stirring often, until softened, about 6 minutes. Add broth, sweet potatoes, salt, turmeric, and cayenne. Bring to a boil over medium-high. Reduce heat to medium-low; cover and cook until potatoes are tender, about 20 minutes.
Skim 1/4 cup thickened coconut cream from top of coconut milk; whisk with 2 tablespoons of the lime juice, and reserve.
Whisk together remaining coconut milk in can and 1 tablespoon lime juice into a medium bowl until smooth, and stir into soup. Place soup in a blender. Remove center piece of blender lid (to allow steam to escape); secure lid on blender, and cover opening with a clean towel. Puree, in batches, until smooth, about 30 seconds. Pour soup into bowls, and drizzle with reserved coconut cream mixture. Top with almonds and cilantro.