Throw the tomatoes into a mixing bowl along with the onion, garlic, vinegar and 3 tablespoons of olive oil. Season with salt and pepper. Gently mix together and leave to macerate.
Toast, grill or bake the pitta breads to give them a bit of colour and to dry them out a little. Leave them to cool before tearing them into bite-sized pieces.
Get a frying pan or griddle searingly hot. Season the steaks generously and then fry them for 2 and a half minutes each side. Remove from the pan and leave them for 5 minutes to rest before slicing them into strips.
Throw the sliced steaks, torn pittas, cucumbers, lettuce and herbs into the mixing bowl. Make sure you add any of the resting juices from the steaks too. Toss everything together. Taste and adjust the seasoning with salt, pepper and lemon juice.
Pile into a serving bowl and garnish with a generous dusting of sumac.