I burnt fire in the ground oven for 4 hours or so. The meat was wrapped in tin foil and damp cloth. I let it simmer in the oven for 3 hours, covering the oven with the flat stones shown on the ground in the picture. To make it more tight I added a layer of sand. For some time I burnt a small fire on top of the covered oven to maintain the temperature. The meat is a lamb shoulder, covered with crushed garlic. It turned out fine and tasty.