NOTE: In addition to or in place of any of the vegetables listed, I have added turnips, large winter radishes, celeriac, and whole mushrooms. Many vegetables taste great when roasted with the chicken juices.
Preheat oven to 375 degrees.
Choose any of the vegetable selections in any combination you like. Cover the bottom of a 9" x 13" glass baking dish or roasting pan with the vegetables. Sprinkle 1 Teaspoon each of salt and pepper, and a tablespoon of olive oil over the vegetables. Use your hands to smear the vegetables thoroughly with the salt, pepper and oil.
Thoroughly wash the chicken, and pat dry. Salt and pepper the chicken cavity, and throw in the garlic cloves and either rosemary or thyme as well. Place the chicken breast side up on top of the vegetables in the baking dish.
Peel the onion and slice crosswise, keeping the onion slices intact, and making each slice about 1/4" to 1/3" wide. Basically you will have about 8 onion "plates" of various sizes.
Run your hand under the breast skin, releasing the skin from the meat. Run your fingers under the legs as well to separate the skin from the meat.
Take the larger onion segments and place them under the skin, 2 segments per side of the breast. Take the smaller onion segments and place them under the leg skin. Any remaining, loose onion slices can be thrown into the cavity.
Slide 6 or 8 sage leaves under the skin, and you can place them on top of the onion slices. Conversely, you can place a sage leaf on each onion segment as you slide the onions under the skin.
Cut the lemon in half, and squeeze the juice all over the chicken, working the lemon into the skin with your hands. Thrown the lemon halves into the cavity.
Rub the remaining olive oil all over the chicken. Sprinkle the remaining salt and pepper over the bird.
Place the bird in the middle of the oven. Baste the bird occasionally with the pan juices that accumulate. The chicken will be done in 80 to 90 minutes. Test the bird for doneness by wriggling the leg, and if the leg comes out of the joint easily the chicken is done.
Let the chicken rest about 10 minutes before carving. To serve, place the chicken on a serving platter, surrounded by the roasted vegetables. Serve the jus on the side.
Recipe courtesy of Food52.