4 ounces whole mild-to-medium-hot dried red New Mexican chiles (16-20 small to medium), stemmed and seeded
2 cups reduced-sodium chicken broth, divided
1 1/4 cups chopped onion
3 cloves garlic, minced
2 tablespoons sherry vinegar or cider vinegar
1 1/4 teaspoons dried oregano, preferably Mexican
1 teaspoon salt
2 1/4 pounds boneless, skinless chicken thighs, trimmed and cut into 1-inch cubes