For the puree, process the chickpeas, yoghurt, tahini, half the lemon rind and 60ml lemon juice in a food processor until smooth. Season.
Place the onion in a heatproof bowl. Cover with boiling water. Stand for 2 minutes, then drain. Combine onion, vinegar and 1 tbs of the remaining lemon juice in a bowl. Season and set aside to macerate.
Heat the oil in a non-stick frying pan over high heat. Add the lamb. Cook, stirring with a wooden spoon to break up lumps, for 3 minutes or until lamb browns. Stir in the garlic, cumin, ground coriander, ginger and chilli to taste. Cook, stirring, for 2 minutes or until aromatic and lamb is cooked through. Stir in remaining lemon rind and juice. Season.
Add broad beans and herbs to onion mixture. Toss to combine. Divide white bean puree among plates. Top with lamb mixture and broad bean salad to serve.