Heat the oil in a medium pot set over medium heat. Add the cauliflower and onion and cook until light golden, about 5 to 6 minutes. Mix in the curry paste and cook 1 minute more. Add the stock and potato. Bring soup to a simmer and cook 15 minutes, or until cauliflower and potato is quite tender.
Puree the soup in a food processor or blender, or in the pot with a hand (immersion) blender. Return the soup to a simmer; season with salt. Ladle soup into bowls. Top each with a small dollop of yogurt and some pumpkin seeds and cilantro, and then serve.
Note: Curry paste is sold in jars in the Asian foods aisle. Patak’s brand was used in this recipe. Pumpkin seeds are available in the bulk foods section.