1. Heat 1 tbsp oil in a wide frying pan. Add 1 pack of the beans, season and cook over a medium-high heat for 10-12 minutes, until charred, blistered and tender. Transfer to a bowl; repeat with the remaining oil and beans.
2. Quarter the preserved lemon and separate the flesh from the skin (discard any pips). Finely slice and set aside the skin. Put the flesh in a small food processor with the harissa, garlic, date (or maple) syrup, lemon juice, 1 tsp of the pickling liquid and1 tbsp water. Whizz to a smooth paste and season, adding more lemon juice to taste.
3. Toss the dressing with the warm beans and spread over a platter. Top with the dukkah and finely sliced preserved lemon skin.