Step 1

For beetroot-yoghurt sauce, preheat oven to 200C. Wrap each beetroot in foil and roast until a knife inserts without resistance (40-45 minutes). Cool, then peel beetroot and coarsely chop. Process in a food processor with remaining ingredients until very smooth, season to taste and refrigerate until required.

Step 2

Pound garlic and 2 tsp sea salt with a mortar and pestle to a paste, add preserved lemon rind, baharat, Aleppo pepper and sumac and pound to a paste (you can also do this in a small food processor). Stir in oil and season to taste. Slash lamb leg at 3cm-4cm intervals, rub spice paste all over and into incisions, cover with plastic wrap and marinate at room temperature for 1-1½ hours or overnight in the refrigerator (bring lamb to room temperature before cooking).

Step 3

Preheat oven to 180C. Place lamb in a roasting pan and roast, basting occasionally with pan juices, until cooked to your liking (1 hour 45 minutes to 1 hour 55 minutes for medium-rare, and internal temperature reaches 54C-58C on a meat thermometer). Cover with foil and set aside to rest for 30 minutes.

Step 4

For parsley and onion salad, bring vinegar and sugar to the boil in a small saucepan, add onion, remove from heat and set aside for 30 minutes to pickle. Drain, reserving a little liquid. Just before serving, add herbs, drizzle with oil, lemon juice and a little pickling liquid, season to taste and toss to combine. Serve salad with roast lamb, beetroot sauce and warmed flatbread.