- Bring a large pan of water to a boil.
- Stir in the salt and lemon slices, then reduce the heat to low.
- Add the prawns and leave to simmer for about 3 minutes until they are cooked through, turn pink and curl.
- Drain the prawns and immediately refresh under cold running water to cool the prawns. Set aside.
- Put the ketchup, horseradish, celery and lemon rind in a bowl.
- Mix well.
- Stir in the lemon juice, salt and pepper.
- Stir in the prawns, then cover and chill for 2 to 3 hours.
- When ready to serve, stir the prawn salad and adjust the seasoning.
- Divide the shredded lettuce between salad bowls and spoon the salad on top.
- Serve at once while the salad is still chilled with lemon wedges for squeezing over.