1. Preheat the oven to 425 degrees . Grate lemon zest into a bowl and add oil, oregano, thyme, rosemary, minced garlic, salt and pepper and stir until incorporated.
2. Halve lemon and place inside cavity of chicken with whole garlic cloves and herb sprigs. Rub all but 2 teaspoons lemon-herb mixture under skin; rub remaining mixture on skin and tie legs together with kitchen twine.
3. Place chicken, breast side down, in a roasting pan or 9-by-13-inch glass baking dish and arrange potatoes, carrots and onion around it. Add stock or water and roast chicken until an instant-read thermometer inserted in a thigh registers 165 degrees and vegetables have browned edges, about 1 1/2 hours.
4. Remove chicken from oven and let rest 10 minutes. Remove skin, lemon, herb sprigs and garlic cloves and discard. Cut chicken into pieces and serve with vegetables.