Bring the water to boil in a large pot and add the tea bags. Turn off the heat and let steep for 10 minutes. Add the rest of the ingredients (except for the turkey) & simmer for about 20 minutes. Remove from heat & cook completely. Soak the turkey with the cooled brine, breast side down, in a clean bucket, large pot, or a cooler with ice. Let it soak for at least 12 hours & up to 48 hours, flipping the turkey halfway through.
Remove from the brine, rinse well, and pat dry.
At this point, I like to rub the turkey with a little melted butter & simply season with salt & pepper. I stuff the inside with a large onion that's been quartered & 1 stick of butter, but you don't have to do that if you don't want to. It's great just with the brine!
Preheat your oven to 275 degrees. Cook at 275 for about 10 minutes per pound. A 20 pound bird would need about 3.5 hours while a 15 pound bird would need about 2.5 hours. After that time, baste the bird really well with the pan juices. Bump the heat up to 350, remove the foil, and return the turkey to the oven until the meat thermometer reaches 165 degrees - basting every so often.
Let the turkey rest for at least 30 minutes before carving. I let mine rest for 45-60 minutes myself.