Box ovens are amazing! They do a great job of cooking food outdoors. Using a box oven is a great way to make cooking with charcoal much more efficient. The box oven keeps the heat contained inside the box instead of allowing heat to escape from the coals into the air. The best thing about a box oven is you can easily make one yourself.
To Make a Box Oven
1 sturdy cardboard apple/fruit box (20 inch x 13 inch and 12 1/2 inch high.)
Heavy-duty aluminum foil
Plastic roasting/cooking bag (for optional window)
HVAC tape (looks like duct tape but shiny like metal)
Spray adhesive (optional)
Cooling rack and 4 soda cans filled with rocks (or a converted portable grill cut to fit)
Blanket for insulation (optional)
Cut out a 4″ x 9” window at the top of one of the sides of the apple box, if desired (note: some heat loss will likely occur through the window). Cut a 1″ x 4” hole on the bottom of both ends of the box to allow air to get to the coals. Tape a piece of the plastic cooking bag (double layer it) over the window area. If there are any other holes in your box (i.e. holes for handles or gaps in the box), cut extra cardboard to make a patch and cover the holes. Cover any cardboard patches with metal tape on both sides of the box (inside and out).
Cover the box completely with aluminum foil inside and out. This works best by spraying the box first with adhesive, attaching foil, and securing with the foil with the aluminum tape. Cover the box well, making sure none of the cardboard is showing so it doesn’t burn. Also note, be sure to cover the box with the foil shiny side out, so it will reflect the heat better. The matte side should be what you stick to the box.
Baking with Your Box Oven
Long handled tongs
Place a sheet of heavy-duty foil (make sure the sheet is longer than your box), shiny side up, on level ground or use a baking sheet. Space soda cans on the foil/baking sheet to support the cooling rack. Position the cooling rack so that only the very corners are resting on the soda cans. Check to make sure the cans aren’t spaced too far apart to prevent the box from fitting over them. You can regulate the temperature of your oven by the number of briquettes you put in it. One briquette equals approximately 35 degrees F(ie. for 350 degrees, use 10 charcoals). Using tongs, place hot briquettes on foil, spreading them out evenly between the cans and along the edges. Don’t pile all of the briquettes in the center because your food will burn. Place them around the edges exactly where the red arrows are pointing at in the image below.
To preheat the oven, place the apple box over the hot coals and empty rack and let it stand for 5 minutes. The charcoal will become whiter as the heat spreads. Once preheated, carefully lift the apple box straight up off the coals and rack, taking care not to tilt it, and place it beside the ground foil, face down. This holds trapped heat in the box. Quickly place your food on the cooling rack that on top of the soda cans and replace the box over the coals.
The charcoal will burn for about 35-40 minutes. When longer cooking times are required, you can add more hot charcoals by slightly lifting the box and slipping them in with long tongs. We found that if a recipe calls for 45 minute baking time and it is warm outside, no additional charcoals are necessary. Remember, one briquette equals approximately 35 degrees F (350 degrees=10 charcoals).