Heat the butter in a soup pot over medium heat on the stove. Add the onion and carrot and sauté until the onion is soft and translucent.
Add the garlic, curry powder, salt and pepper and stir to incorporate for 1 to 2 minutes, until the spices are fragrant. If the mixture is too dry at this point, add 2 tablespoons of the coconut milk and whisk until the spices incorporate smoothly.
Add the corn, white beans, vegetable broth, and remaining coconut milk. Increase the heat to medium-high to bring to a gentle boil, then cover the pot and decrease the heat to medium-low and simmer for 10 minutes. Remove from the heat.
Working in batches, carefully transfer the soup to a blender, and purée until smooth. NOTE: Do not fill the blender more than halfway as hot liquids will steam and expand! Also, remove the center cap from the lid and use a thick dish cloth to cover the opening so the pressure does not build up inside. Start blending on a very low speed and increase slowly until the mixture is smooth. Transfer the puréed soup to a separate pot or a large bowl and then repeat with the remaining soup.
After all the soup is puréed, add the lime juice and a few dashes of hot sauce, if using. Stir well.
Taste and adjust seasonings, as necessary, to your liking.
Serve warm with garnishes of extra corn kernels, sliced green onions, extra hot sauce, and freshly cracked black pepper, if desired.