Mix together half the finely chopped chilli, lime zest and juice, garlic and oil, then pour over the prawns. Cover and chill for 20 mins to marinate.
Meanwhile, put the lentils in a pan, cover with twice their depth in water, bring to the boil, then simmer for 15-20 mins until tender. Top up the water if you need to.
To make the dressing, put the remaining chopped chilli, the soy, honey and vinegar into a small bowl and stir together. Drain the lentils, then tip into a large bowl. Spoon over almost all the dressing while the lentils are hot, tip in the sesame seeds, then mix well.
Heat a frying pan until really hot. Lift the prawns out of the marinade, then fry for 1-2 mins each side until pink and lightly golden. Pour in the marinade and bring to the boil.
Fold the chopped coriander through the lentils, then spoon onto serving plates. Top with the prawns and any pan juices.