Introduction: Hot Rock Kalua Pig
In Hawaii they cook whole hogs underground with hot rocks and banana leaves. It's called Kalua Pig and it is Amazing. I set out to replicate this delicious and wonderful pork on a smaller scale in my backyard without having to dig a big ol' hole and cook an entire pig. In the process I built a dual purpose grill and hot rock BBQ.
The cooker is built from 2 dozen cinderblocks, dirt, rocks and a few other materials that you probably have on hand. With this inexpensive setup you will be able to have a two day Meatfest starting with your favorite grilled vittles and culminating in amazing Kalua pork.
Here is the disclaimer: This cooker involves heating rocks to a dangerous temperature and then covering them with potentially flammable vegetation and then leaving it unattended for many hours. If you are careless or unlucky you might burn up.
To build the cooker you will need:
24 CINDERBLOCKS - these cost me $30. This was the only thing I had to buy other than the pork.
1 STEEL OR IRON GRATE - must fit over the cooker. I borrowed one from a weber, but i didn't quite fit and I had to use a pipe to stabilize it. I bet an oven rack would be perfect!
DIRT - cheap! suitable locations for the cooker were not suitable for digging, but less conspicuous areas provided plentifully. I used one wheelbarrow full.
ROCKS - cheap or free. DANGER! USE CAUTION HERE!!! Some stones, especially those collected from a body of water could explode when heated. This might be bad for your health and livelihood. Fair Warning OK? Choose rocks sized between softball and cantaloupe. You want a couple dozen rocks.
PIECE(S) OF PLYWOOD - to cover the cooker during slow cooking. Serves to keep the heat in and keep out potential weather and varmints.
CLOTH - helps hold in the heat for slow cooking; I used an old bed sheet.
To operate the cooker you need:
FIREWOOD - You will burn wood to grill with but the most important thing is to thoroughly heat the rocks for slow cooking. It will take 3-4 hours for the stones to get hot enough.
GREEN LEAFY BRANCHES, PLANT STALKS OR SOAKED WOOD - You need enough to create a moist buffer layer between the hot stones and the pork. The authentic material is freshly cut banana tree stumps. It's wet and fibrous and doesn't burn up, so it creates tasty, smoky steam to cook the pork. In the Mid-Atlantic U.S. I had to use something more local and went with maple and hickory branches with the leaves still on. You could try some other materials too; any type wood that is used for cooking/smoking should work well here. I want to try corn stalks next.
BANANA LEAVES - This is to wrap and flavor the pork. I can get frozen banana leaves at the Latino market near my house for $1 a package. If you can't get banana leaves, you could use foil, but then it won't be Kalua Pig.
CHICKEN WIRE - optional - this helps to cradle and maneuver the pork but you could do without it...
THE MEAT THE MEAT THE MEAT - For day one, pick your favorite grilling foods; steaks, burgers, sausages, chickens, pork chops, lamb, bacon, offal and vegetables too!
For day two it's slow cooking and pork is king. Get a great big pork shoulder, with the skin on. I use the whole shoulder; it should weigh close to 20 pounds. You could do it with less, but it would seem like a lot of work for a little product. This oven is probably capable of cooking two or three whole shoulders if you wanted to. I haven't tried yet.
Step 1: Build the Cooker
First, find a suitable safe place to build your cooker. There is going to be a big hot fire in it, so take proper precautions. Do I need to be more specific? Don't burn anything down or cause property/bodily damage! Ask someone who knows you well if you have any common sense before attempting this step alone. I built my oven on the concrete walkway in my backyard so not to kill a spot on the lawn, but it could be done on bare ground, provided that it is very level.
Stack the blocks on the ground in three layers of eight blocks, as pictured, to produce an open cube shape. The blocks should be straight and level, without big gaps. Be sure that the blocks are stable and will not be knocked over later when you fill them with heavy stones and fire and pork! Now is a good time to check that your grilling grate fits across the top of the cooker.
Next, fill it in with a few inches of dirt, I used a half wheelbarrow full to give about 4 inches of coverage across the bottom of the cooker.
Last step is to cover the dirt with the rocks that you collected.
Step 2: Start the Fire
Start the fire a few hours before you plan to eat on the first day, probably in the mid-afternoon. The rocks need several hours of steady blazing fire to heat up and the best grilling happens towards the end of the burn when you are down to a tremendous bed of coals and glowing rocks.
Start the fire just like you might start a campfire. Then feed it logs to keep it going strong until you have a beautiful bed of coals.
Step 3: Prepare the Pork
While you wait for the rocks to get hot, take some time to prepare the pork shoulder for cooking.
First, lay out a square of chicken wire, about 2 feet on a side. You may omit this step, but it makes handling the cooked pork much easier.
Lay out several layers of banana leaf over the chicken wire.
Place the pork shoulder in the center of the banana leaves. If one side has better skin coverage, put that side down. Now salt the meat generously. Think about how much salt you would need to season the meat through and through... Don't add any other seasonings. I know that might be hard for most BBQ fans, but trust me, with this method the banana leaves and salt are all the flavors needed. You can sauce the meat later when it is cooked and pulled if you want to.
Now bundle the pork up in the leaves to completely cover it and use the chicken wire to hold it in place.
It's ready for the pit! By the way, i let the shoulder sit out to come to room temperature for a couple hours before it goes in the cooker.
Step 4: Time to Grill
At this point the fire has been burning for 2 or three hours and you have a wonderful bed of coals. So put your grill grate on top of the blocks and have a weenie roast! The only advice I have is that this badboy gets a lot hotter than your kettle grill. Things cook fast and you will want some loooong tongs!
Step 5: The Pit and the Pork
The moment is now to entomb the pork sarcophagus! Look at the glowing hot rocks!
So now you should make a nice soft bed to rest the pork in. Here I am putting wet hickory and maple branches over the hot rocks. Go for about 6 inches of bedding.
Now lower in the pork!
Cover the pork package with more wet branches.
Now put a wet sheet or burlap cloth over the leaves and branches. Leave a little hanging out so you can grab it later.
Now shovel on a few inches more dirt over the sheet to insulate the cooker.
The last thing to do (before praying that nothing goes wrong) is to cover the cooker with plywood. Be sure to cover the tops of the cinder blocks too, a lot of heat convects out of the holes otherwise. I had to use some extra planks 'cause the plywood didn't reach far enough.
Now Wait......12-14 hours should do it. Feel free to enjoy the good smells emanating from the cooker.
Step 6: The Delicious Discovery
Now that 12 to 14 hours have passed, you can disinter the pork and discover what has been happening inside the cooker!
Take off the ply wood and remove two layers of cinder blocks from one side of the cooker. Now it is easy to grab the edges of the cloth and pull all the dirt off the top of the cooker in one motion. Peel back the branches and remove the pork. This is where the chicken wire come in handy cause the meat will be juicy and hot and slippery. Have a large platter nearby!
Unwrap the banana leaves and reveal the Kalua Pig!