Dig a pit in the ground about 1 meter wide and 0.5 meters deep. Line the pit with stones and build a fire inside. Allow the fire to burn until the stones are hot and the fire is reduced to embers.
Season the chicken, pork, and lamb with salt and pepper. Place the meat in a large container or basket. Arrange the potatoes, carrots, kumara, and onions around the meat.
Place a layer of cabbage leaves on the bottom of the pit to prevent the food from sticking to the hot stones. Carefully place the meat and vegetables on top of the cabbage leaves.
Cover the food with additional cabbage leaves. Using long-handled tongs or a shovel, cover the food with hot stones. Then, cover the entire pit with a layer of soil, making sure it is well-sealed to trap the steam.
Allow the food to cook for 3 to 4 hours. The steam and heat from the stones will cook the meat and vegetables slowly, infusing them with a unique, smoky flavor.
After the cooking time has passed, carefully remove the soil and hot stones from the pit. Unwrap the cabbage leaves to reveal the cooked food. Serve the Hangi directly from the pit or transfer it to a serving dish.
Enjoy your meal!