To get the best roast chicken with crispy skin without overcooking the flesh, try opening up and flattening, or spatchcocking, the chicken. It's much easier if you have a good pair of poultry shears.
To test for doneness, insert the probe of a meat thermometer into the thickest part of the breast from the inside without puncturing the skin.
Boil water, add all the ingredients and let cool for 20 minutes. Strain and keep cool in refrigerator till needed.
Place the chicken on a cutting board with breast side down and the legs pointing towards you.
Using shears, cut along each side of backbone about 1-1/2” apart, cutting through the rib bones as you go from the front to the back. Remove the bone (you can save for stock or roasting for gravy).
Make a deep cut at the sternum cartilage in the centre of the breast, then press to flatten and remove the cartilage that pops up.
Turn chicken over and remove the wishbone connecting the two breasts on the front side.
Lay chicken, breast side up on the rack over a baking sheet.
With the marinade injector, inject the brine into each breast and leg from the inside cavity. Retract the skin when injecting, any holes may tear the skin when roasting.
Leave chicken on the tray in the refrigerator until needed. (May be done up to 4 days in advance.)
When ready to cook, preheat oven to 200 F.
Cook chicken until it reaches an internal temperature of 150 F, which should take about one and a half hours. Remove chicken from the oven and let cool.
Increase oven temperature to the hottest possible, between 450 F and 575 F. Carefully return chicken into the oven, and roast for 5 to 7 minutes to get the chicken crispy and golden without burning the skin. Oven will smoke heavily, so make sure you have hood fans on high and windows opened.
Rest the chicken for at least 10 to 15 minutes before carving.