For a gas-burning oven, just turn the knob, push the ignition button and adjust the flame. If you have got a wood-burning oven, build a fire in the centre of the oven using some sticks of dry kindling then add some pieces of hardwood as the fire gets going. Then add some logs of about 5-10 cm in diameter to form enough embers.
Of course, the bigger the oven, the more firewood you will need to reach the cooking temperature. In the larger models, we recommend moving the fire all over the oven floor to heat it evenly. Use dry, seasoned hardwoods to avoid dense, black smoke that could ruin your dishes.
