Re the cracking in Tandoori ovens..
The first time I used mine, . I put in Charcoal briquettes and had it going like a blast furnace..obviously being a man only read the instructions the next day ..The instructions read...
Do not use fire briquettes during the first burn and for the first 3 sessions of tandoorAnyway, next morning after reading the instructions gingerly emptied out the ashes and b()llocks the bottom was all crazed

... Just about sh1t myself, and had a lump in my throat felt like blubbing , wife not happy!! Spent a miserable morning the Phew !!! saw the Australian site, so no harm done ;D..
http://tandoorliving.com.au/domestic-tandoor-care-maintenance.html. Been raining here a lot so have only been able to use a couple of times at weekends. Have had a high casualty rate with the Naan's though as they wouldn't stick, so out of 6 only got three to eat so that worked out at 1/2 naan each.

very nice they were though

I don't think the oven is fully seasoned yet..The site also mentioned that......
" Mix 1 tablespoon of salt into 0.5 litre of luke warm water and wet a sponge or cloth with the salt solution. Squeeze the excess salt solution from the sponge/cloth and gently wipe the damp sponge/cloth over the wall of the Tandoor. Rinse the sponge/cloth in the salt solution and repeat until the wall has been fully wiped over. Do not wet the clay liner too much. Allow the Tandoor to dry. After the Tandoor has been fired for a total of 6 hours you will be ready to start cooking naan and roti bread. This salt solution wipe will assist with the naan and roti bread sticking to the Tandoor wall. The process can be repeated every now and then as in addition to assisting with naan/roti sticking, it also assists with removing soot that can develop over time on the Tandoor wall.
There are also a few recipes that look as though they are worth a whizz.
http://tandoorliving.com.au/Tandoori-cuisine-recipe-indian-curry.htmlCheers
Jocko
But the Tandoori chicken was excellento!