Saute the onions, mushrooms and spices in the olive oil until brown.
Add the chicken.
When the chicken has browned, reduce heat and allow to simmer until cooked and aromatic (this process should take aprox. 20 mins).
To prepare tacos, place a table spoon of yogurt at the base of each, add some lettuce and top with mince and mushroom filling. Then sprinkle with more lettuce and cheese.
Beaf or pork mince can be used for equally delicious results.