Take a stockpot and place it over medium heat. Add water and all of the brine ingredients except turkey to a boil.
Let the mix boil until sugar and salt are dissolved. Remove from heat and let cool to room temperature.
Place the turkey in the stock pot and make sure it's completely covered. Refrigerate overnight.
Preheat the oven to 400° and remove the turkey from the brine. Pat dry the turkey using paper towels and stuff the cavity with red onion, apple, and garlic.
Season the turkey with salt and pepper and brush it with melted butter.
Tie the turkey legs together and place them on a roasting rack over a large roasting pan.
Roast until the turkey turns golden in color and the thickest part of the thigh reads 165°. It should take 1 hour 30 minutes to 2 hours to cook.
Let the turkey cool for 15-20 minutes before slicing.