The In-Ground Hog Pit

Cooking underground is one of the oldest ways to roast a whole animal. A pit is dug, heated with a long fire, and the wrapped meat is buried to cook slowly in the trapped heat. Here is how the method works and what to watch out for.

An ancient method

People around the world have cooked in earth ovens for a very long time. The Hawaiian imu is the best-known example in the United States: a pit lined with hot stones, used to cook kalua pig wrapped in leaves and covered with earth. Mexican barbacoa was traditionally cooked in an underground oven, and the New England clambake steams seafood over hot rocks. The in-ground hog pit used for backyard pig roasts borrows the same principle: heat the ground and stones, bury the meat, and let time do the work.

How it differs from a block pit

In a cinder-block pit, you tend live coals for hours and can watch the meat. In an in-ground pit, you put the meat in and cover it, and you cannot easily check on it until it comes out. The cooking is more like steaming and roasting than smoking. The meat comes out extremely tender and moist, with a smoky, earthy flavor, but without the crisp bark or skin of an open pit unless you crisp it afterward.

Is in-ground right for you?

You need the right site. Diggable soil with no buried utility lines, a safe distance from buildings, trees and roots, and permission from the property owner. In the U.S., call 811 before you dig so underground lines can be marked.
Check local rules on open fires and burning.
It is labor. Digging, a long fire, and unearthing a heavy hog.
It is less predictable. Soil, moisture, weather and the size of the hog all affect timing. Have a leave-in thermometer with a long cable or wireless probe if possible.

Equipment

Shovels and a wheelbarrow.
Dry rocks for lining the pit, such as river rocks that have been fully dried, or bricks. Wet or porous rocks can crack violently when heated; avoid rocks taken from water.
A large quantity of hardwood.
Wrapping: plenty of heavy-duty foil, and traditional coverings such as banana leaves where available. Some cooks use chicken wire around the foil to make lifting easier.
Burlap sacks or similar covers, soaked in water, plus a large tarp to lay over before the dirt.
Heat-resistant gloves, long tools, thermometers, and a hose or water supply.

The process

Dig the pit. Make it larger than the wrapped hog in every direction, with enough depth for the rock layer, the hog and a thick layer of covering. Pile the soil nearby for reburying.
Line it. Set a layer of dry rocks or bricks in the bottom.
Build a long fire. Burn hardwood in the pit for several hours to heat the rocks and the surrounding soil thoroughly. Keep adding wood until you have a deep bed of coals.
Prepare the hog. While the fire burns, season the hog, keep it cold until wrapping, and make sure it is fully thawed. The USDA Food Safety and Inspection Service (FSIS) warns that meat cooked slowly while still partly frozen spends too long in the "Danger Zone" of 40 to 140 °F. Wrap the hog in leaves if using, then in several layers of heavy-duty foil, then chicken wire if you want handles.
Level the coals. Rake the coals and rocks into an even layer. Add a layer of damp leaves or wet burlap to protect the meat from direct contact.
Bury it. Lower the wrapped hog in, cover with more wet burlap, lay a tarp over the top, and shovel soil over everything until no steam or smoke escapes.
Wait. The hog cooks for many hours. Mark the spot and keep people and pets away.
Unearth carefully. Remove soil gently, peel back the tarp and burlap, and lift the hog out by its wire or with plenty of help. Watch for steam and hot coals.
Check the temperature. Use a food thermometer in several thick places, especially hams and shoulders. FSIS lists 145 °F with a three-minute rest as the safe minimum for whole cuts of pork. If the meat is not done, finish it in a smoker, oven or grill.

Serving

Unwrap on a large table or in big pans; the juices will be plentiful. Pull the meat, mix it with its juices, and season with salt or vinegar sauce. If you want crisp skin, put pieces on a hot grill for a few minutes. Keep served meat at 140 °F or above, and refrigerate leftovers within two hours (one hour above 90 °F), as FSIS advises.

Closing the pit

Let the coals cool and drench them thoroughly with water before refilling the hole. Buried coals can stay hot for a long time, so do not leave a partly filled pit unattended and mark it until it is fully cooled and backfilled.

Safety summary

Call 811 before digging; avoid utility lines and tree roots.
Use dry rocks only; wet rocks can burst.
Never use gasoline or paint thinner to start the fire, as FSIS also warns.
Keep the area marked and supervised.
Use a thermometer; do not guess.

Sources

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