For two 21 pound turkeys I did the following:
In a large stock pot, place:
6 qts. vegetable broth
4 cups sea salt (you could get away with 3 cups)
4 T crushed dried rosemary
4 T dried sage
4 T dried thyme
3 T dried savory
1 cup brown sugar
Boil until salt and sugar dissolve.
Let cool to room temperature.
After removing innards and giblets, wash turkeys thoroughly.
Place each turkey in separate large Williams-Sonoma Brining Bag.
Ladle boiled broth over turkey in bags dividing evenly between the two turkeys.
Add 2 qts. vegetable broth (room temp) and 1 gallon ice water to each bag, seal bags and
mix broth by kneading the bags.
Make sure the turkeys are covered and the brine has filled each turkey cavity.
If the turkey isn't completely covered, you will need to flip the turkey 1/2 way through
the brining process. This amount covered my turkeys just fine.
Put bags in roasting pan for stabilization and put in the fridge for 12-24 hours. I did 18 and
it was fine.
Cooking:
Remove turkeys from brine and rinse thoroughly inside and out. Pat dry with paper towels.
Stuff each bird with 1 onion cut up, 4 stalks of celery cut up, salt, pepper, thyme, rosemary, and sage.
Use a skewer to hold flap of skin closed on neck end and tie/bind legs together at the other end.
Rub entire turkey with thick coat of butter.
Place on roasting rack in a roasting pan and cover with a foil tent allowing space in between
turkey and foil.
Pre-heat oven to 325oF. Insert thermometer in thickest part of thigh without touching the bone.
Place in oven.
Notes:
We put our turkeys in the oven at 7:30a.m. for a 1:00p.m. luncheon. I had to raise the temperature to 350 a few times to speed cooking. The turkeys weren't done until 1:15. We should have put them in at 6:30 - 7:00a.m. Let them cook until the temperature reads 170 (not 165 like everyone says) degrees.
Let turkey rest for 20 minutes before carving.