Preheat oven to 450 degrees. Season chicken with salt and pepper. In a large roasting pan with a rack, cook chicken, skin side up, until an instant-read thermometer inserted into thickest part of thigh registers 165 degrees, about 45 minutes. Remove chicken and rack.
Make sauce: Pour pan juices into a measuring cup; skim off fat. In pan, cook wine over medium-high, scraping up bits, until reduced by a fourth, 4 to 6 minutes. Add broth, lemon juice, and pan juices. Cook until reduced by a fourth, 5 minutes. Stir in oregano. Add water, if needed, to make 1 1/2 cups.
Serve two chicken halves with 1/2 cup of the sauce.