TWO DAYS BEFORE THANKSGIVING BRINE THE TURKEY.
SLICE THROUGH THE SKIN WHICH SEPARATES THE BREAST FROM THE THIGHS. PRESS DOWN ON THE THIGHS TILL THEY POP OUT OF THE JOINT.
DISSOLVE 7 TO 10 TBSPS OF FINE SEA SALT (DEPENDING ON THE SIZE OF YOUR TURKEY) IN 3 QUARTS OF BUTTERMILK.
LIGHTLY CRUSH BUT DON'T BOTHER PEELING GARLIC CLOVES. PEEL AND CUT LENGTHWISE ONION INTO EIGHTHS.
PUT ALL THE INGREDIENTS, INCLUDING THE TURKEY IN TWO 13-GALLON GARBAGE BAGS. SET IN A LARGE BOWL. FORCE OUT AS MUCH AIR AS AS POSSIBLE AND TIGHTLY SEAL THE BAG.
REFRIGERATE FOR TWO DAYS TURNING THE BIRD OVER EVERY 12 HOURS OR SO.
REMOVE THE RACKS FROM YOUR OVEN SO THE TURKEY CAN SIT ON THE BOTTOM.
PUT THE BAG IN THE SINK. RELEASE THE TURKEY FROM THE BAG AND WIPE OFF AS MUCH OF THE BRINE AS POSSIBLE. ALLOW IT TO WARM TO ROOM TEMPERATURE.
PRE-HEAT OVEN TO 450º.
HEAT A LARGE, HEAVY-DUTY ROASTING PAN OVER TWO BURNERS ON TOP OF THE STOVE. ADD SPLASH OF PEANUT OIL.
DRY THE SKIN SIDE OF THE SPLAYED TURKEY WITH PAPER TOWELS. LAY THE TURKEY IN THE ROASTING PAN SIDEWAYS SKIN SIDE DOWN, SO THE THIGHS MAKE CONTACT WITH THE BOTTOM OF THE PAN. BROWN OVER MEDIUM HEAT FOR A FEW MINUTES, PRESSING DOWN ON THE THIGHS A FEW TIMES SO THEY MAKE CONTACT WITH THE BOTTOM OF THE PAN.
MEANWHILE, PEEL A LARGE ONION, SLICE LENGTHWISE IN HALF, THEN IN 3/4-INCH HALF MOONS.
REMOVE THE TURKEY FROM THE STOVE. TUCK THE ONIONS AROUND THE BIRD. POUR IN ABOUT A 1/2-INCH OF WHITE WINE.
ROAST FOR 45 MINUTES AT 450º, THEN REMOVE FROM THE OVEN.
INSERT A RACK IN THE MIDDLE OF THE OVEN. REDUCE THE HEAT TO 375º
ROAST ANOTHER HOUR OR SO, UNTIL THE THIGH MEAT REGISTERS 165º ON AN INSTANT THERMOMETER. IF THE SKIN TURNS TOO DARK, TENT WITH FOIL UNTIL IT'S DONE.
REMOVE FROM THE OVEN AND SET ON A WARM SERVING PLATTER. TENT WITH FOIL AND ALLOW TO REST FOR 30 MINUTES BEFORE SERVING.
SERVES 8-12 DEPENDING ON THE SIZE OF THE TURKEY.