Cook the lentils in a large saucepan of boiling water for 20 minutes or until just tender. Drain. Refresh under cold running water. Drain.
Meanwhile, combine the mustard seeds, cumin, turmeric and half the lime rind in a large bowl. Add the prawns. Toss to coat. Heat 1 tbs oil in a large non-stick frying pan over high heat. Cook the prawns, turning, for 2-3 minutes or until golden.
Place the snow peas in a heatproof bowl. Blanch with boiling water for 30 seconds. Drain. Refresh under cold running water. Drain.
Combine the lentils, snow peas, shallot, tomato, salad leaves and coriander in a large bowl. Stir in 2 tsp juice and remaining 2 tsp oil. Combine yoghurt, remaining rind, juice and extra turmeric in a bowl.
Transfer the lentil mixture to a large serving plate. Top with the prawns, dressing and extra coriander. Serve with extra lime wedges.
