Step 1

Melt the butter in a large saucepan or Dutch oven over medium-high heat. Add the onions, bell pepper, and jalapeño and cook, stirring frequently, until softened, 5 to 7 minutes. Do not brown. Add the flour and cook, stirring constantly, for 1 minute.

Step 2

Add the broth, 1 cup of the milk, salt, cumin, coriander, and potatoes; bring to a boil. The soup will seem thick; that’s okay. Reduce the heat to low, cover, and simmer, stirring once halfway through so the potatoes don’t stick to the bottom of the pan, until the potatoes are tender, 12 to 15 minutes (if your potatoes are not tender at this point, just continue simmering until they are).

Step 3

Meanwhile, in a blender, puree the remaining 1 cup of milk with 1 cup of the corn until smooth.

Step 4

Add the milk and corn mixture to the soup along with the remaining 2 cups of corn; simmer until hot. Off the heat, stir in the sour cream, scallions, and cilantro. Taste and adjust seasoning, if necessary. Ladle the soup into bowls and serve with lime wedges.

Step 5

Note: I like this soup a little spicy, so I mince about half of the jalapeño’s seeds and ribs and toss them in with the onions and peppers. If you’d like more control over the heat, you can add cayenne pepper at the end, to taste, or offer hot sauce at the table.

Step 6

Note: To scrape the corn from the cobs, place the corn on a clean dish towel set over a cutting board, then use a serrated knife to cut the kernels of the cobs. (The dish towel prevents the kernels from bouncing all over the place.) Alternatively, you can invert a small bowl inside a larger bowl. Hold the cob upright on top of the inverted small bowl, with the flatter end of the cob down, and use a sharp knife to slice downward as close to the cob as possible.