Place the oil and onion in a large pot and sauté over medium heat until the onion is translucent but not browned, about 5 minutes. Add the garlic, ginger, and curry powder, and sauté for 30 seconds, stirring constantly to keep the garlic from burning. Add the water and carrot to the pot, cover, and bring to a simmer for 30 minutes to make a very light stock.
Remove the carrot from the stock and add the papaya chunks. Simmer for 2 to 3 minutes more, just to heat the fruit.
Purée with a hand blender or in a blender or food processor and season with salt and pepper. Serve warm or at room temperature, garnished with a dollop of yogurt, a sprinkle of black pepper, and a few strands of lime zest.
Photo by Doug Bradshaw.