To prepare the lamb, blend the garlic, onion, oregano, olive oil and the zest from 1 lemon, until you reach a smooth marinade. Cover the lamb with the marinade and refrigerate for 24 hours.
Pre-heat oven to 140°c (fan forced).
Prepare a baking tray with approx. 2 cups of water and place the lamb inside on a wire rack and cover with foil.
Place in heated oven to roast for approx. 4 ½ hours or until the meat falls off the bone. Baste with the pan juices every hour during cooking.
Remove lamb from the oven and allow meat to rest for 30 minutes.
Increase oven temp to 220°c.
Remove the bones from the lamb shoulder. Place the meat on to baking tray skin side up.
Drizzle with olive oil and the juice from 1 lemon and return to the oven for 10 minutes to caramelise.
To make the pita bread, place flour, salt and yeast into a mixing bowl. Stir in water, olive oil, honey and yoghurt until all ingredients are combined.
Transfer dough to a lightly floured bench and knead for 5 minutes until smooth.
Please kneaded dough into a large, oiled, bowl (approx. twice the size of the dough) and cover with cling wrap. Leave to rise for 1 hour.
Lightly knead again to knock back the dough, dividing dough into 12 (80g) balls.
Roll the dough balls out until they’re approx. 5mm thick and sprinkle with semolina to prevent sticking.
Prick all over the surface with a fork, place onto a tray and allow to rest for 10 minutes.
Prepare a non-stick frying pan over a med/high heat.
Lightly spray the pan with olive oil and cook each for 1 minute per side. Set aside until ready to assemble.
To make the mustard aioli, add the egg yolks, vinegar and mustard into a suitable bowl and whisk until combined.
Then, slowly add the sunflower oil while continuing to whisk to emulsify the mixture. Once thick, season to taste.
For the soused onions, roughly cut the brown onions into a 1cm dice.
Add onions, vinegar, water, sugar to a saucepan and a generous pinch of salt.
Bring to the boil and then simmer down until the onions soften, and the liquid reduces to a syrup. Keep aside.
For the chips, cut the potatoes into 15mm chips.
Place into a saucepan and cover with cold salted water.
Bring water to the boil, and then simmer until chips are just cooked. Strain and spread out onto a tray to cool.
Once the chips are cold, heat fryer oil to 150°c. Gently place the chips into the oil and fry for approx. 3 minutes.
Remove from the oil, drain well and place onto absorbent paper to drain. Cool in the fridge uncovered until required.
To serve, heat fryer oil to 180°c. Add the chips and fry until crispy and golden. Drain excess oil and toss with salt and oregano.
To assembling the souva, brush the pita with olive oil and heat either on the BBQ or in a pan to warm through.
Add a spoon full of the mustard aioli to the pita.
Top with chunks of the lamb, some of the soused onions, a handful of the chips and some sprigs of the flat leaf parsley.
Serve either open or wrapped with greaseproof paper.