Steam pit filled with hot rocks and food, being covered with pine boughs for the vegetation layer.

The steam pit is one of those traditional cooking methods that is a fair bit of work, but it’s also worth the trouble. If you’ve been to a real Luau or a New England Clam Bake, you have enjoyed the results of a steam pit (or steam mound). These cooking techniques use a hole or mound with hot rocks at the bottom, with layers of dirt, vegetation and food above the hot rocks. The heat of the rocks produces steam from the dirt and vegetation, cooking great tasting food that stays hot for hours until you’re ready to eat it.

To start out, a pit of varying depth and width is dug in the dirt, clay or sand. The pit can be as small as one foot deep and one foot wide, or as big as you need if you have enough hot rocks and food to fill it. I typically dig two feet wide and a foot and a half deep to cook for a few people, but I once dug a steam pit as big as a grave to cook 72 fish for a large group.

Next you’ll need rocks and lots of firewood. Select suitable rocks from a high, dry location. These rocks are placed in the bottom of the pit to see how many it will take and where the stones fit best. You have a choice now of leaving the stones in the pit and building the fire on top of them, or taking the rocks out of the pit and placing them in a big fire. Either way the stones should be heated for two hours.

If you heat the rocks in the pit, you must scoop the remaining wood, charcoal, coals and ash out of the pit when the rocks are hot enough. The wood, ash and charcoal will give the food an unpleasant “wet smoked” flavor otherwise. If you heat the rocks outside of the pit, you can use a shovel to scoop them up and move them into the pit. You can also just roll them or slide them with a stout pole.

Once the pit has the hot rocks in it, cover them with an inch or two of dirt or sand. Then place 6 to 8 inches of vegetation over the dirt. Next, put your food in a single layer, with the things that need the most cooking in the center and the other foods around the edges. Leave a few inches of space between the foods and the wall of the pit for even cooking. Then cover your food with another 6 to 8 inches of vegetation.

Once you have your food in the pit between layers of vegetation, you can cover the pit with the dirt from digging the hole. A layer of bark, mats or cloth could go on before the dirt to make dirt removal easier when the cooking is done. When the final dirt goes on, your work is done. Just come back three or more hours later, dig up your food, and enjoy.

Tips for working with a Steam Pit:

• A “rock kettle” can make a good steam pit, but you’ll still have to dig up some dirt to cover it.

• Work quickly to get your vegetation and food in the pit so that your hot rocks don’t cool off too much before you seal the pit.

• A few cups of water poured over the top layer of green vegetation will generate more steam and conduct heat to your food more efficiently.

• Use enough dirt on top so that no steam is seen escaping.

• In freezing cold weather, you may need to build a fire on top of the pit.

• If the ground is cold and/or very wet, use a thin layer of small or thin rocks before putting in the bigger hot rocks. This will keep the soil from conducting away too much of the rock’s heat.

A wide variety of non-toxic vegetation can be used in Steam Pits. Here is a partial list of materials that are good — and some materials to avoid.

Good Steam Pit Vegetation:

  • Grasses, sedges, cordgrass, cattail leaves, reeds and rushes edible weeds like amaranth, lamb’s quarters
  • Leaves and leafy branches of mild smelling and tasting trees like maples and willows
  • Good tasting and smelling leaves of sassafras and spicebush
  • Seaweed (but watch out for sea lice and other little sea creatures)
  • White Pine needles (and most other pines, except for ponderosa and loblolly pines which may be toxic)

Toxic or Foul Tasting Vegetation:

  • Oak, walnut and tulip poplar leaves — Foul tasting
  • Buckeye and horse chestnut tree leaves — Toxic
  • Cherry tree leaves — Become deadly poison as they wilt
  • Pokeweed leaves and stalks — Toxic to poisonous
  • Rhododendron, laurel and most evergreen shrubs — Toxic to poisonous
  • Iris leaves and jimsonweed leaves — Toxic
  • Some ferns — Toxic
  • Any unknown herbs, weeds, wild flowers or shrubs — Potentially toxic

Please tell us in the comments if you have done this technique, or just enjoyed the results of this great outdoor cooking method.