People around the world have cooked foods underground for many years. Methods for cooking meats underground vary widely by culture and resources available. Modern adaptations make barbecuing and smoking meat in underground pits a favourite for BBQ enthusiasts. An underground BBQ pit smoker can be built among friends in an afternoon. The process of digging the hole may, in some cases, be much faster than the act of cooking in it. A backhoe is the recommended way to dig a pit these days. If a shovel is the method of choice, get friends to help tackle the job.
Dig a hole in the ground three feet wide by four feet long. Dig the hole a minimum of three and a half feet deep. It should be square in shape. The hole needs to be deep enough to hold at least one foot of coals and the food that will cook in it. Volcanic rock is optional and when added will speed cook time.
Soak a mixture of aromatic hardwoods in a bucket of water overnight.
Start a large, hot fire in the hole. Continue to add wood to the blaze, until a bed of hot coals one foot deep is produced. The burn time for this process can take as many as six hours. Place two fire bricks at each end of the hole and on the sides to hold the cooking grate.
Wrap meats in wet burlap sacks. Make a cage for the meat, wrapped in burlap, with chicken wire sewn closed with bailing wire. Make a set of long bailing wire handles and attach them to the chicken wire cage. This will be handy for removing the meat from the pit once it's cooked.
Place sheet tin near the hole for a fast cover. When the wet smoking chips are placed in the hole, steam and smoke will rise. Sheet tin keeps fire directly off the meat allowing for slow and even cooking.
Drain the water out of the bucket of smoking chips. Spread the chips evenly along the bottom of the smoking BBQ pit. Place the cooking grate in the hole, ensuring levelness. A grate can be made from concrete reinforcing wire that's free of rust. A window well grate is a good option for a cooking grate as well.
Insert the sheet tin over the grate and place the food on top. Cover the food with the second piece of sheet tin. Back-fill the hole with dirt. Seal the edges of the BBQ pit well to decrease flare ups in the pit.
Prepare for a 10 hour, or more, cook time on large portions of meat.
Size the pit according to the meat that will cook in it. When building a permanent BBQ smoking pit, use fire brick on the sides for a professional appearance. Stuff cavities of meat with apples, onions, spices and potatoes for a gourmet feast. Beans or other side dishes cook easily in the hole in cast iron cookware. Use a meat thermometer to determine readiness.
Never use galvanised metal unless it has passed through a hot fire to burn off chemicals.