¼ cup (½ stick) unsalted butter
2 onions (12 oz/ 340 g), chopped (about 2 cups)
Kosher salt and freshly ground black pepper
2 garlic cloves, chopped
2 teaspoons ground cumin
2 teaspoons chili powder
8 cups (1.2 kg) corn kernels from 8 cobs or the same amount frozen
2 russet potatoes (about 2 lbs/910 g), peeled and cut into
¾-inch (2-cm) pieces
8 cups (2 L) chicken stock from Whole Poached Chicken, or Vegetable Stock
3 tablespoons fresh lime juice
4 ounces (115 g) Cotija cheese, crumbled
Fresh cilantro leaves, for serving
Heat the butter in a large pot over medium heat. Add the
onions, 2 teaspoons salt, and 1 teaspoon pepper. Cook,
stirring often, until the onions are translucent and soft,
10 to 12 minutes. Add the garlic, cumin, and chili powder
and cook until fragrant, 30 seconds to 1 minute more.
Reserve ½ cup of the corn kernels to use as garnish
and set aside. Stir in the remaining 7½ cups corn, the
potatoes, and stock, cover, and bring to a boil. Reduce to
a strong simmer. Cook, stirring here and there, until the
potatoes are completely soft, 15 to 18 minutes.
Purée the soup, using a blender in batches or a
handheld immersion blender. Stir in the lime juice and ½
teaspoon salt.
Serve the soup topped with cheese, cilantro, reserved
corn kernels, and a few grinds pepper.