Make small slits all over the prime rib and fill each slit with a slice of the garlic and sprig of rosemary.

Place in large bag and pour in 1 tin lager or cider.

Let marinate overnight in refrigerator.

Preheat oven to 350 degrees F.

Place in roasting pan and pour liquid in with it.

Season liberally with the salt and coarse pepper, and roast for about 2 hours until medium-rare, or until a thermometer inserted into the centre of the meat registers 135 degrees F.

Remove the meat to a platter, and tent with foil to keep warm.

Place the roasting pan on top of the stove over 2 burners set on high heat.

Add remaining lager to the pan drippings in the pan and cook over high heat until reduced, scraping the bottom of the pan with a wooden spoon.

Add the stock and cook until reduced by half.

Whisk in the thyme and season with salt and pepper, to taste.

If desired, thicken with corn flour or roux.

Slice meat as desired and serve with thyme au jus.