Add the lemon slices to the drippings in the pan; cook over medium-high heat, undisturbed, until charred on the bottom, about 1 minute. Remove the pan from the heat. Add potatoes, shallots, thyme, oregano, rosemary and the remaining 1/2 teaspoon salt to the pan, stirring to coat. Nestle the chicken into the mixture in the pan. Bake for 15 minutes.