Preparation :
Mix yeast with water and make it into a paste. Peel and strain tomatoes. Chop the peppers thinly. Grate the onions. Mix the yeast, yoghurt, tomatoes, peppers and onions in a bowl until they turn into a thick liquid. Start kneading the mixture by adding flour gradually. Knead the dough until it becomes very thick.
Flour a tray, put the thick dough on the tray and cover it with a piece of cloth. If the dough is in a warm place it will puff up in 1 hour, if it is in a cool place it will puff up in 5-6 hours. When the dough has puffed up, remove it from the tray and knead well. Then put it on the tray as before and cover it. Go on with the same procedure until the dough no longer puffs up. Now that your tarhana is ready, you can take a piece of the dough and see that it breaks without skretching. Form the dough into small pieces, place pieces on a cloth and let them dry. Check the pieces as often as possible for drying. Crumble the dried pieces. (It is necessary to check the dough often, because if the dough dries too much, crumbling gets more difficult.)
When crumbling is over, put the crumbles in a fine sieve and sieve then, put tarhana in dry jars and cover with lids. Your tarhana is now ready for cooking.