"Reverse Sear" is a low and slow cooking method intended to preserve, as much as possible, the moisture within the meat, then crisping the outside in a very hot over for presentation. The benefit is that it allows an irregularly shaped piece of meat, or a very thick one, to be cooked evenly without overcooking the outside. The disadvantage is that, because the meat is maintained in a very low oven for an extended period, your sanitation must be impeccable. Not just above reproach, but awe-inspiring comment worthy sanitation.
This is how you make prime rib without a thick, unappealing grey ring around the outside - or a perfect medium rare leg of lamb shank, even though one end is 3x thicker than the other (or more).
Basically, the chunk of protein is seasoned, set on a pan, and cooked at as low a temperature as the oven will manage (but definitely below the boiling point) - I target between 185 and 200 degrees) until it reaches about 5 degrees* of target temp. You *must* have a good probe thermometer. Its then removed from the oven, covered in aluminum foil, and tented to rest. Carryover will finish cooking it to desired degree of doneness. Meanwhile, the oven is cranked up and allowed to heat thru - 450+. Once the oven has reached temp, the foil tenting is removed and the protein is placed back into the oven for the skin to crisp, a bit of fat to render, etc for table presentation. and because the temps should stay below boiling the whole time, very little moisture is given up by the beast. HOWEVER - raw veggies like garlic, onion, etc which might normally cook via normal (hotter) cooking methods likely will not have the desired textures, if they are completely cooked at all - many of them require steam to be released, rupturing their cell walls and expanding starches to achieve traditional mouth feel.
Anyhow, its a thought. I use it routinely for big chunks of beef, lamb, pork, etc. I've never had a bird big enough to consider it - but a 42# turkey??? I'd try it once (not on guests) to see if its appropriate there.
