Preheat the oven to 425 degrees F.
To ensure even cooking, remove chicken from the refrigerator, and let it stand at room temperature for 30 minutes. If the chicken comes with a plastic pop-up thermometer, discard it; the readings are often inaccurate. After rinsing the chicken inside and out with cold running water, dry it with paper towels. Tuck the tips of the wings under the bottom to keep them from burning.
Place onion slices in 2 rows in a heavy-duty roasting pan to form a bed for the chicken. The onions will flavor the chicken and the pan juices that form the base of the gravy. To help release the lemon's essence, roll it back and forth with the palm of your hand pressing on top, then pierce the surface all over with a fork. Put garlic, thyme, and lemon inside the chicken's cavity.
Set chicken on the bed of onion slices, breast-side up. Then bring legs forward, cross them, and tie them together with about 18 inches of kitchen twine. (Tying the legs is much simpler than trussing the bird, which requires tying the body.)
Spread butter over the entire exposed surface of the chicken; this ensures even browning. Sprinkle well with salt and pepper.
Place the chicken in the oven and roast until the skin is a deep golden-brown color, and the juices run clear when the chicken is pierced. If the skin is browning too fast, tent with foil. Check the internal temperature of the breasts and the thighs with an instant-read thermometer. When ready, the reading in the deepest part of the breast should be 180 degrees F, and in the deepest part of the thigh it should be 190 degrees F.
When the chicken is finished cooking, remove it from the pan, and transfer it to a cutting board with a well to catch the juices. Let the chicken stand at room temperature for up to 20 minutes. The juices, which rise to the surface when cooking, will settle and redistribute evenly throughout the chicken. While it rests, make the pan gravy.
Untie the legs of the chicken. Remove the lemon, garlic, and herbs from the cavity of the chicken; discard. Place the chicken on a serving platter breast side up, and, using a sharp knife, carve the bird; use a large fork to pull 1 of the legs away from the body. With the tip of your knife, find the joint that connects the leg to the body, and sever it. Cut the thigh away from the drumstick at the second joint. To remove the breasts, cut straight down between the breasts, following the contour of the rib cage, until you hit the wishbone. Cut through the joint where it meets the breastbone. Serve the individual pieces, or cut the breast into thin slices for a more elegant presentation.
Pan juices from roast chicken
1 cup homemade chicken stock or low-sodium canned chicken broth
1 tablespoon unsalted butter
While the chicken rests, pour the pan drippings into a shallow bowl or a fat separator, leaving the onions in the pan. Using a fat separator or large spoon, skim off and discard as much of the fat as possible.
Pour the remaining drippings and juices back into the roasting pan. Place pan over medium-high heat, and cook for about 1 minute. Add chicken stock, and raise the heat to high. Using a wooden spoon, deglaze the pan by stirring up any brown bits baked on the bottom so that they combine with the stock; these brown bits add flavor to the gravy. Cook until the liquid is reduced by half, about 4 minutes.
Strain into a small bowl, pressing down on the onions with the back of a spoon to extract any remaining liquid; discard the onions. Stir in butter until it is fully incorporated. Serve immediately.
Yield: 2/3 cup
(c)2004 Martha Stewart Living Omnimedia, Inc. All Rights Reserved.