
The day before roasting, first thing in the morning, make your brine. Mix salt and water together until dissolved.
Place the brining bag in the bucket and put the bird in breast-side down. Pour the brine into the bag, making sure the entire bird is covered - no naked bits. Zip the bag up, cover, and put it in the fridge. If you don't have space in your fridge, you can use a cooler.
Refrigerate for 12 hours.
Take the turkey out and rinse under cold water. Pat dry with paper towels, making sure to dry the inside of the cavity, too.
Return to the refrigerator in a roasting pan and let air-dry overnight.
The day of roasting, preheat your oven to 350 degrees Fahrenheit.
Combine butter, garlic, and thyme in a bowl until soft. Set aside.
Carefully, using your fingers, peel the skin away from the turkey breast (you may have to break a membrane; that's OK) and rub the butter mixture under the skin.
Truss the turkey.
Rub the outside of the skin with the oil and season pepper. I know, I know; it's so hard not to sprinkle salt all over the skin at this point! But please, don't. Your bird is already plenty salty from the brine!
Roast turkey breast down for 2 hours. After 2 hours, flip the turkey very carefully so that the breast side is up and return to the oven for 30 minutes to finish cooking and browning the skin on the breast.
Remove the turkey to a cutting board and cover with foil; let it rest for 20 minutes. Slice the turkey and serve hot.
While the turkey is resting, put the roasting pan on a burner over low heat, sprinkle in the flour, and stir to incorporate any liquid in the pan.
Gradually add the turkey stock, stirring constantly. Transfer the gravy into a small pot, and simmer over low heat until it has the preferred consistency.
Add additional pepper to taste and strain the gravy through a fine-mesh sieve before serving.