Add the lamb to a bowl and mix together with the olive oil, lemon zest and juice, garlic and oregano. Season with a good grind of salt and pepper, stir well and cover with cling film. Leave to marinate in the fridge for a couple of hours or longer if you have time.
When you are ready to cook you need to heat a barbecue until its really hot. You can also cook these inside on a cast iron griddle, preheated on the hob until smoking-hot.
Thread the lamb and shallot quarters on to the skewers and grill for about 8-9 minutes, turning a few times so they cook evenly.
Whilst the kebabs are cooking, warm the flat breads or pittas by wrapping them in foil and laying on the grill bars, or warming in the oven.
To serve, use a fork to pull the meat and shallot from each skewer and onto the centre of each flatbread or stuff inside a pitta. Top with a little tzatziki and a cucumber and tomato salad and tuck in.