How to Make It
Heat a small skillet over medium-high heat. When hot, add the jalapeño and the large green chiles. Dry-roast, turning occasionally, until the chiles are blackened all over, about 7 minutes. Add the chiles to a bowl, cover and let sit for 10 minutes. Peel off the chiles’ skin (It is fine if some charred bits remain on the chiles.) Remove the chile’ seeds and discard. Finely chop the chiles.
Meanwhile, in a small bowl, combine the sour cream and lime zest and juice.
In a large saucepan set over medium heat, add the oil. When the oil shimmers, add the onion and garlic and cook, stirring occasionally, until the onion softens and browns slightly, about 10 minutes. Add the cumin, oregano and chopped chiles and stir for about 30 seconds. Add the ground chicken, broth and salt. Bring to a boil and simmer until the chicken is cooked through, about 10 minutes. Finish with the cilantro and scallions. Serve with the lime sour cream.