Mix all ingredients for brine in a medium-sized pot except the ice and water. Bring to low simmer.
Simmer for 1 min and turn off heat. Add ice and stir. Liquid should be cool to the touch.
Place turkey in large receptacle and pour brine over turkey. Add remaining water to ensure turkey is fully submerged.
Brine for 12 - 18 hrs, or about 1 hr per lb of turkey.
Preheat oven to 450°F.
Remove turkey from brine. Discard brine and pat dry turkey with paper towel.
Sprinkle cavity with kosher salt and place ½ of the onion, ½ of the orange, and half of the herbs inside.
Truss legs together to close cavity. Use additional twine to keep the wings close to the body and the cavity closed.
Line roasting pan with turkey neck, remaining onion, orange and herbs, then pour in chicken stock.
Place turkey on roasting pan insert breast side up and place in oven.
Roast for 20 min, or until skin begins to turn golden brown. Lower heat to 325°F. Cover turkey loosely with aluminum foil, shiny side down.
Continue to roast turkey until meat thermometer inserted into thickest part of the thigh reaches 165°F.
Let rest for at least 30 min or up to 2 hrs before carving and serving.