You may have already faced some of the pizza cooking challenges that I did: It was hard to get the pizza onto the hot stone, the pizza stuck to the stone, accidental calzones, the bottom burned before the top was even cooked, burned wrists, and generally mediocre pizza. I set out to overcome these challenges for myself. I tinkered in my garage and invented the Pizza-Porta (not on the first try). Along the way I have learned a lot of tricks about cooking pizza on a ceramic, kamado style grill. I hope these tips are helpful for you. Please feel free to pass these along to your friends whether they are Kamado Joe Pizza fans, Vision Grill Pizza fans, or Big GReen Egg Pizza fans.
Nothing stirs up more discussion than lump brand. I am brand agnostic, but there are a couple of attributes of charcoal that truly interfere with cooking pizza. The first is to watch out for brands that create a great deal of flame even after being fully engulfed as they put off a chemical odor. This odor will be absorbed by the crust. The second challenge is lump size. Filling the firebox with huge chunks of charcoal results in lower temperatures for various reasons. While It is helpful to place large pieces in the bottom so that you don't choke the airflow, a mix with chicken-egg size lump reaches higher temperatures. Conversely a bag of tiny chips makes a solid mat and chokes your airflow. (See my interview with Jonathan at Rockwood for the detailed story)
The intense heat of a kamado grill is the result of its airflow design. Air is sucked in the bottom to replace the air expelled out the top. The hotter it gets, the faster this air is expelled and faster it is drawn into the bottom. If the charcoal or deflectors or stones impede the airflow, it will impede this furnace tendency. Use a Kick Ash Basket as it is self-clearing when small chunks of charcoal drop toward the bottom. Also, overlap half-moon deflectors in the middle to ensure that there is plenty of space around the edges for airflow. Make sure that airflow gaps are wide to reach high temperatures. (Chad at had some pointers in our interview)
One quick lesson learned is that wind is not good for grilling. Try to position your grill so that wind does not blow into the top or side vents. Rotate the grill or place it around the corner of a building to shield it from direct wind.
There is a hot fire directly underneath the pizza stone. This is the source of all the heat, and unfortunately for baking, it is all concentrated below the cooking surface. To balance this concentration of energy, the grill must be set up so that the heat is reflected off the bottom of the pizza stone and passed around the edges to heat the ceramic surfaces on the sides and top of the dome.
The goal for a more Neapolitan style pizza is to have the dome temperature super-hot (>750F) and the stone oven floor nearly the same temperature. This of course is not the natural tendency of a kamado grill. Using a plate setter or deflector stone is the first obvious step, but there a couple of cautions: 1) When it is placed legs up and set down in the three slots of the fire ring, the platesetter may limit your airflow, keeping the grill from reaching high temperatures. 2) Using the platesetter with legs up and the cooking grate to hold the stone does allow heat to sneak around the plate setter and heat the bottom of the stone. 3) Never set the pizza stone directly on the plate setter. This will just transfer all of the heat to the pizza stone making it too hot to cook. Even adding ceramic parts like bricks or tile between the deflector and the stone will transmit energy into the pizza stone. It is critical that there is a kind of escape valve for this heat energy in the form of an air gap. This gap will allow the heat from the top of the plate setter to dissipate before reaching the pizza stone. Using the stainless grate and some additional material like pipe fittings or balls of aluminum foil is a great solution. (The cast iron grate does not serve very well to provide this air gap because its mass carries heat from the edges into the bottom of the pizza stone.)
For additional deflection, shielding can be added under the pizza stone. A heat shield needs to reflect radiant energy and shed energy. Using an aluminum foil disk underneath the pizza stone is a great addition to an air gap. This thin layer reflects the radiant energy that comes off the plate setter and keeps the pizza stone temperature a bit lower. An aluminum pizza pan also serves a similar function of creating a radiant barrier that keeps the pizza stone from overheating.
Stands and racks
There are a number of stands and racks available. Any device that lifts the pizza stone off of the plate setter and increases the air gap can be beneficial. A double rack like the Pizza-Porta RCL rack, serves this purpose and also allows more capacity. Having two stones gives flexibility in cooking between the top and bottom stones.
There is variability in pizza stones. The kamado manufacturers all provide a type of stone that is heavy duty enough for 700F + degree cooking. Some kitchen supply companies make pizza stones that are for home ovens and only stand up to 500F degree pizza cooking. The importance of the stone is to provide a surface that will retain enough heat to cook the bottom of the pizza. The porosity of the stone is claimed to benefit the crust by drawing in moisture. Buy a stone that is heavy enough to withstand high temperatures and will provide a suitable surface for your cooking style. Thermarite is a more durable material than firebrick. Beware of pizza stones that are larger than the diameter of the platesetter/deflector as they will block airflow and they will receive energy directly from the fire without the benefit of deflection.
Heat Retention in a Pizza Stone
Each raw pizza placed on the stone will bring the cooking surface down 30-40F degrees. In a wood-fired oven, the pizzaioli will spin a pizza in place to take advantage of this. It is important to consider this when planning for a party. If the stone will be sitting empty in the grill 10-15 minutes between pizzas, the temperature will climb between each one. Be cautious when cooking the next pizza. Add extra deflection, a slightly lower temperature, or cook a couple pizzas in succession to get the temp back down.
Lighting a kamado grill for pizza is not a trivial detail. There are differences between lighting for a 250F degree cook and a 600F+ cook. For pizza at 600F you need a big fire. Use an absolutely full load of fresh lump. Then, light the lump in a number of places on the top so that the fire can spread to engulf more of the fuel. Allow the fire to get established as you are loading in all of the internal components. Leave the top dome open for a few minutes and let the fire get big. Make sure that all of your ceramics (plate setter, pizza stone and oven walls) soak in heat for 30 minutes before cooking your first pizza. A pizza will stick to a stone that is less than 400F.
All the above advice is generic to kamado grill cooking. Here are some pointers to setting up the Pizza-Porta in your kamado grill. The best way to get up to pizza temperature is to light the lump in a number of places around the edge. Next, place the racks and stones. Leave the dome open for a few minutes to get the fire established. Finally, place the Pizza-Porta with side vents closed in the grill and close the dome. Leave the chimney vent and bottom vent open fully for maximum airflow. The temperature will rise slowly as it is heating the ceramic of the walls, deflectors, stones etc. As the grill approaches 500F degrees, close off the top chimney vent and open the Pizza-Porta vents. The temperature may drop a bit before climbing again toward 600-650. Once your stone is over 400F you can begin cooking. The stones and ceramic walls take about 20-30 minutes to soak in enough heat to start cooking. Once you have dialed it in, the temperature should be consistent for hours of cooking. If it creeps above your target, throttle it down with the side vents and the bottom vent. Some grills, even of the same brand, seem to heat faster than others - in the pizza business they say “know your oven.” More on why the Pizza-Porta is important HERE.
Cooking on a kamado grill is a truly rewarding experience. The grill is very forgiving and most everything you do will result in great cooking results. Pizza seems to be the most challenging food on this style of grill because heat is lost every time the dome is opened. This guide is a starting point. Take your time, have fun, and develop your own solutions.
Make sure to seek advice from bloggers and chefs who make a living making great pizza. Wood-fire pizza places are a great place to learn.