1. Position an oven rack just below the center of the oven and preheat the oven to 400 degrees F.
2. Set out roasting pan without rack.

For the Chicken

1. Juice half of the lemon into a small measuring cup and add avocado oil. Next, combine the rosemary, thyme, sage, salt, pepper, and parsley flakes in a small bowl. These mixtures are for the outside of the chicken. 
2. Rinse the chicken under cold water and pat dry with paper towels, then salt the cavity with a large pinch of salt. Place garlic cloves, yellow onion half, and half of the lemon in the cavity and tie the legs together loosely with kitchen string. Place the chicken in the roasting pan, breast side up.
3. Carefully loosen the skin over the breast area, taking care not to tear it. Drizzle half of the avocado oil mixture on the breast side of the bird and rub into and under skin. Flip the bird and pour the remaining oil mixture over the back. Be sure to rub wings legs, and sides of the bird as well.
4. Sprinkle back of bird with about 1/3 of the seasoning mixture and rub into back and sides. Flip  so breast side is up and rub some of the spice mixture under the breast skin, then sprinkle the remainder over the skin and legs. Place chicken in a roasting pan.

For the Vegetables

1. In a small bowl, combine thyme, sage, rosemary, salt, pepper, and garlic powder.
2. Place cut vegetables in a large bowl and drizzle with 2 tablespoons olive oil to coat evenly. Sprinkle with seasoning mixture and toss again to coat evenly. Arrange the vegetables around the chicken (in a single layer, if possible) and add the broth. 
3. Roast covered for 45 minutes (if roasting pan does not have a lid, cover the entire top of the pan with foil), then remove and continue roasting until the vegetables are tender and a meat thermometer inserted into the thickest part of the thigh of the chicken reads 170 degrees F (remember, 165 is the minimum and 180 may be dry). A 4-pound chicken may take up to an hour and 45 minutes and a 5-pound chicken will take just over two hours.
4. Remove from oven and transfer bird to a platter, then tent loosely with foil and rest for 15-20 minutes. Transfer vegetables to a bowl and cover with foil to keep warm.

For the Gravy

1. Scrape the bottom of the roasting pan and strain liquid into a fat separator cup. Pour the separated pan juice into a sauce pan and discard the fat. Bring the juice to a boil over medium-high heat then lower to medium to reduce liquid to serve as-is.
2. If thicker gravy is preferred, thicken to a gravy with a slurry of 1 tablespoon tapioca flour or arrowroot flour mixed with 1-2 tablespoons cool water. Add slurry slowly and whisk constantly until desired thickness is achieved (you may not need all the slurry mixture).