Preheat the oven to 350°F.
Mix the seasonings together and set aside.
Shake the flour inside the oven roasting bag, then put the bag in a roasting pan.
Add the garlic, onion and carrot to the bag.
Rub melted butter over the turkey and then rub in the seasoning mixture.
Put the turkey on top of the vegetables in the bag.
Have the roasting bag with the open part facing the side not upwards.
Close the bag and seal with twine, then cut 5 slits into the part of the bag facing upwards.
Put the roasting pan in the oven and cook for 2 hours or until the turkey is 180°F in the thickest part of the thigh.
Take it out of the oven and let it rest in the bag for 15 minutes, then carve and serve.