Preheat the oven to its maximum temperature (as close to 300°C/570°F as possible). If you have a pizza stone or tile, place it in the oven (or leave your baking tray in the oven so it will preheat).
Sift the flour into a mixing bowl and add the salt. Make a well in the middle and slowly pour in 125ml (½ cup) of lukewarm water. Knead the dough for 5 minutes. Sprinkle some flour on your work surface and then divide the dough into four balls. Cover the bowl with a damp cloth and leave to rest.
Score a shallow cross in the base of the tomatoes, then transfer to a heatproof bowl and cover with boiling water. Leave for 30 seconds, and then plunge in cold water and peel the skin away from the cross.
Cut the tomato in half and scoop out the stalks and seeds with a teaspoon. Roughly chop.
Remove the seeds from the capsicum and roughly chop. Coarsely blend the tomatoes and capsicum with the capsicum paste, garlic, parsley, chilli flakes, pepper and salt. Combine the mixture with the lamb mince and stir thoroughly.
Place a ball of dough on the floured work surface and, with floured hands or a rolling pin, flatten into a round about 25cm (10in) wide and less than 5mm (¼in) thick. Repeat with the remaining dough balls.
Using a tablespoon thinly spread the lamb mixture onto the rounds. Then press in with your hands.
If you are using a baking tray, take it out of the oven and put a piece of baking paper over it. Dust the baking paper with a little wholemeal flour.
Place the rounds of dough on the baking paper and bake for about 5 minutes, or until the edges are crisp.
Meanwhile, to make the salad, finely slice the onion and place in a bowl. Sprinkle with salt and sumac, add the lemon juice and olive oil, and then mix together with your hands.
Sprinkle the salad over the lahmacuns, squeeze on some lemon juice, and serve.
