A tunnel oven including a case enclosing a baking chamber, the baking chamber having a lateral side, an oppositely lateral side, a longitudinal end, and an oppositely longitudinal end, the case having longitudinal and oppositely longitudinal end walls respectively bounding the baking chamber's longitudinal and oppositely longitudinal ends; the tunnel oven further including first and second food passage ports respectively extending through the case's longitudinal and oppositely longitudinal end walls, the first food passage port having lateral and oppositely lateral sides; the tunnel oven further including a heater connected operatively to the case; the tunnel oven further including a food conveyor extending longitudinally through the baking chamber; the tunnel oven further including a plenum mounted within the baking chamber's lateral side, the plenum being opened by a blower port and by at least a first duct port; the tunnel oven further including an air blower mounted in communication with the plenum's blower port; the tunnel oven further including at least a first air duct mounted in communication with the at least first duct port; and the tunnel oven further including at least a first air curtain port further opening the plenum, the at least first air curtain port being positioned for directing air toward the first food passage port's lateral side.