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 cumin seeds in a small skillet and toast 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 one or two 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.

Garnish: Cut the tortillas into 1" x ¹/₄" strips. Mix the ground cumin with the 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.

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.