Griddled Chicken with White Wine Jus

Name: Griddled Chicken with White Wine Jus
Ingredients: 1 (2 1/2- to 3-pound) whole chicken; 2 1/2 teaspoons kosher salt, plus more to taste; 3 tablespoons olive oil, divided; 1 carrot, cut crosswise into quarters; 1 celery stalk, cut crosswise into quarters; 1 shallot, halved lengthwise; 1/4 cup (2 ounces) dry white wine; 1 1/2 cups chicken stock (such as Bare Bones Chicken Bone Broth); 1/2 teaspoon black pepper; 1 tablespoon cold unsalted butter; 2 tablespoons finely chopped fresh flat-leaf parsley; 1/2 teaspoon fresh lemon juice; Cooked polenta