The present invention provides improved outdoor cooking systems and methods in various styles for cooking food in an efficient and consistent manner, with little required monitoring or action by the user. Embodiments of the cooker of the present invention include an upper cooking vessel which may be removably engaged with a separate base, a removable fuel basket, and a bottom air intake opening having a diffuser cap above it that not only disperses incoming air flow to the perimeter of the vessel for a more even burn and consistent cooking chamber temperature, but also directs ash and drippings from the food being cooked away from the intake opening. This prevents the intake opening from being clogged, and makes the drippings available for evaporation to provide moisture inside the cooker. The intake opening is adjustable allowing a user to control the amount of air flowing into the cooking chamber.