Preheat oven to 425° F.

Remove the chicken giblets. Rinse the chicken, inside and out. Remove any excess fat and leftover pinfeathers and pat the inside and outside dry. Place the chicken in a roasting pan. Liberally salt and pepper the inside of the chicken. Stuff the cavity with the bunch of thyme, two rosemary sprigs, both halves of the lemon, and all of the garlic. Brush the outside of the chicken with one tablespoon of the olive oil and sprinkle again with salt and pepper. Tie the legs together with kitchen string and tuck the wing tips under the body of the chicken.

Place the onion slices, potatoes and carrots in a large bowl.  Add remaining tablespoon of olive oil; sprinkle with salt and freshly ground pepper.  Toss to coat.  Scatter onion, potatoes and carrots around the chicken.

Roast the chicken uncovered for 1½ hours, or until the juices run clear when you cut between a leg and thigh. Remove the chicken to a platter and cover with aluminum foil for 15 minutes.

Optional Gravy:   Remove all of the fat from the bottom of the roasting pan, reserving 2 Tablespoons in a small cup. Add the chicken stock to the pan and cook on high heat for about 5 minutes, until reduced, scraping the bottom the pan. Combine the 2 Tablespoons of chicken fat with the flour and add to the pan. Cook, stirring constantly until thickened. Boil for a few minutes to cook the flour. Strain the gravy into a small saucepan and season it to taste.  Yield:  4 to 6 servings.