Brush the pitta bread with 1tbsp of olive oil and bake in the oven for 2mins each side to crisp slightly.
Heat 1tbsp of oil in a frying plan, fry the shallots for 4 mins until softened. Add the lamb mince, garlic, cumin, salt and pepper and fry for 7 mins on a high heat till brown. Add green peppers and mushrooms and fry for another 3 mins.
Spread the tomato puree on the pitta and share the lamb equally over the 4 pittas. sprinkle with cheese and put in the over for 4 mins. Serve topped with a spoonful of yogurt and coriander.