Mix the lamb, mint, cumin, aleppo pepper, garlic, red onion and a sprinkling of salt and pepper together in a bowl. Form into four patties. Heat a drizzle of vegetable oil in a frying pan over a high heat. Cook the burgers for 5-7 minutes on both sides then place on a plate and keep warm.
Place the sliced pepper and onion on a baking tray and mix with the olive oil along with a little salt and pepper. Place in the oven for 30 mins.
Meanwhile mix together the yoghurt, chilli paste and one crushed garlic clove. Stuff each flatbread with a quarter of the vegetables and feta, a burger, coriander leaves and a scoop of yoghurt.