I love the combination of sweet, spicy and smoky, and this soup delivers that in abundance. I used a chipotle pepper, which is a smoked dried jalapeno, it gives the soup the heat and the smokiness. —The Cautious Vegetarian
Place the chipotle into a small heat-proof bowl. Cover with boiling water and let sit for 15 minutes or so.
Heat the oil in a large pot over high heat. Add the onion and celery; reduce the heat to medium and sauté, stirring, until the vegetables start to get tender, about 3 to 4 minutes. Add the garlic and cumin seeds and stir until aromatic, about another minute. Add the potatoes, vegetable broth and a pinch of salt.
Squeeze the water out of the chipotle chilli, remove and discard the seeds, chop finely and add it to the soup. Bring the mixture to a boil, reduce the heat to medium low and simmer for 15 minutes.
Meanwhile, cut the kernels from the cobs (alternately, you could use 2 cups (480 ml) of frozen corn that you have thawed). Add the corn to the soup and simmer for 10 minutes longer. Taste for salt.
Combine the olive oil, lime juice, lime rind and cilantro in a small bowl. Divide the soup into bowls, spoon on a dollop of sour cream, drizzle with the oil mixture and serve immediately.