Here is a luxuriously thick soup that is very low in calories, especially if you leave out the tortilla chips. You really boost the corn flavor by adding cobs to the broth. Indeed, anytime you have leftover cobs kicking around, especially at the end of the summer, you might want to cook up a corn broth and salt it away in the freezer in anticipation of those long, cold winter months. Then it’s a snap to make this soup using your frozen broth and a box of frozen corn. If you are not in the mood to fry your own tortilla strips, you can certainly buy some good store-bought chips and just crumble them on top.
Kosher salt and freshly ground black pepper to taste
1 tablespoon finely chopped fresh cilantro
To make the soup, cut the corn from the cobs, reserving the cobs. Pour the stock into a large saucepan or soup pot. Add as many of the stripped corn cobs as the pot will hold, discarding the rest. Bring to a boil over high heat. Reduce the heat to medium-low and simmer, partially covered, for 15 minutes.
Place the cumin seeds in a small skillet and toss over medium-high heat, stirring or shaking the skillet often, until slightly darkened and fragrant, about 3 minutes.
Melt the butter in a separate soup pot or kettle over medium heat. Add the onions, celery, jalapeños, and toasted cumin seeds. Cook, stirring often, until the onions and celery are softened, about 5 minutes. Reserve 1 1/2 cups of the corn kernels for garnish and stir the remaining kernels into the onion mixture. Remove the cobs from the stock and pour the stock over the vegetable mixture. Bring to a simmer over medium-high heat. Season with salt and pepper. Reduce the heat to medium-low and cook, covered, stirring often, until the corn is very tender, about 10 minutes. Remove from the heat and cool slightly.
Working in batches, puree the soup in a blender. Strain through a fine mesh strainer, pushing hard on the solids to extract as much liquid as possible. Pour the soup into a large saucepan and season with salt and pepper.
To make the garnish, cut the tortillas into quarters, then cut each quarter into 1- by 1 1/4-inch-wide strips. Mix the ground cumin with the 1/2 teaspoon salt in a small bowl. Pour enough oil into a deep, saucepan to measure about 1 inch. Heat over medium high heat until almost smoking. Add the tortilla strips, a few at a time, and fry until browned and crisp, about 1 minute. Drain on paper towels. Sprinkle with the cumin salt while hot.
Preheat the broiler to high and adjust the rack so that it is about 6 inches from the heat. Place the red pepper on a broiling pan and broil, turning often, until charred on all sides. Transfer to a resealable plastic bag and seal. Set aside for 15 minutes or until cool enough to handle. (The steam will loosen the skin from the pepper.) Remove the core, skin, and seeds from the pepper and cut into julienne strips.
Just before serving, bring the soup almost to a boil over medium high heat. Stir in the lime zest and lime juice, season with salt and pepper, and pour into warmed bowls. Garnish with the reserved corn kernels, the tortilla strips, the red pepper strips, and a pinch of the chopped cilantro.