chicken paprikash recipe

2 to 2 1/2 pounds chicken pieces, preferably thighs and drumsticks Kosher salt 2 to 3 tablespoons unsalted butter 2 pounds yellow onions (about 2 to 3 large onions) Freshly ground black pepper to taste 2 tablespoons sweet paprika, preferably Hungarian 1 teaspoon hot paprika or cayenne, or to taste 1 cup chicken broth 1/2 cup sour cream