In a saucepan, melt butter over medium heat. Add minced onion and finely chopped celery; cook until clear. Add chicken broth, chopped artichoke hearts, and olive oil.
Bring to a boil. In a separate bowl,whisk together lemon juice and cornstarch. Stir into the boiling liquid and continue boiling for 5 minutes, stirring constantly. Stir in half-and-half and heat through. Season with salt and pepper.Servings: 6