In a high-speed blender or food processor, combine the fresh mango cubes and mango nectar. Purée for about 30 seconds until completely smooth.
Add the coconut milk, sour cream, fresh lime juice, curry powder, and a pinch of sugar to the blender. Process again until the mixture is velvety and fully combined.
Taste and adjust sweetness with more sugar if needed.
Transfer the soup to a sealed container and chill in the refrigerator for at least 1 hour, or until thoroughly cold.
To serve, ladle the chilled soup into individual bowls. If using, arrange a few thin slices of jalapeño in the center and garnish generously with julienned mint leaves.
