2. Rinse the chicken with cold water and pat dry it dry with paper towels.
3. Grate the zest of the lemon and mix it with 1 1/2 tablespoons of the rosemary and garlic. Sprinkle the mixture evenly in the cavity of the chicken. Cut the lemon in half, squeeze 2 tablespoons of the lemon juice on the outside of the bird and put the lemon halves inside the bird.
4. Place the chicken on a rack in a roasting pan. Sprinkle it with salt and pepper.
5. Place the chicken in the oven. After 15 minutes turn the heat down to 350°F and continue roasting the chicken.
6. When the chicken has been in the oven for a total of 45 minutes, combine the potatoes, carrots and peas together in a bowl. Add the remaining rosemary and the olive oil and toss to combine. Put just the potatoes (they take longer) on a baking sheet and place it on the rack below the chicken.
7. After the potatoes have roasted for 15 minutes, add the remaining vegetables to the potatoes. Continue to roast the chicken and the vegetables separately until the chicken juices run clear when the thigh is pierced with a knife and the vegetables are tender, about 30 minutes more. (If the chicken and vegetables are not fully cooked at exactly the same time, remove the cooked item and keep warm, while the other finishes cooking.)
8. Transfer the chicken to a serving platter and let it rest for about 10 minutes. Remove and discard the skin. Carve the chicken and serve it with the vegetables.