The rich, fertile soil of Sonora, in northern Mexico, makes for happy cows that produce some of the country’s best milk and cheese. This mildly spicy soup, a chowder of sorts made with milk, chiles, tomatoes, potatoes, and cheese, shows off that wealth of good dairy. The cheese of choice, queso Chihuahua, is a melting cheese that is a mainstay of the region. But Oaxaca, asadero. mozzarella, or even Monterey Jack can step in as dignified substitutes. Any type of potato will work.

3 tablespoons canola or safflower oil
1 to 1 1/4pounds potatoes (4 medium), peeled and diced (about 3 cups)
1 1/2 cups chopped white onions
1 cup diced green bell peppers
1 ripe medium tomato, cored and diced
4 poblano chiles (about 1 pound), roasted, peeled, seeded, and cut into strips
3/4 teaspoon kosher or sea salt or to taste
4 cups chicken broth, homemade or store-bought
2 cups milk
8 ounces white melting cheese, preferably queso Chihuahua, Oaxaca, asadero. mozzarella, or Monterey Jack (see headnote), diced (about 1 1/2 cups loosely packed)

Heat the oil in a large heavy pot over medium heat. Add the potatoes and onions and cook, stirring often, until the onions are soft and translucent, 4 to 5 minutes. Add the bell pepper, tomato, poblano chiles, and salt and cook until the vegetables are softened, 4 to 5 minutes. Add the broth, bring to a simmer, and cook for 10 minutes, or until the potatoes are tender and the broth has thickened a bit. Taste and adjust the salt. Reduce the heat to medium-low and slowly add the milk, then bring to a gentle simmer. Gradually add the cheese and stir until it is completely melted. Taste again for salt. Top with a little scallion for color, if desired.