1. Defrost the prawns and drain, if using frozen prawns.
2. Mix the mayonnaise, cream, tomato puree and lemon juice in a bowl and fold in the prawns.
3. Divide the mixture between the 8 slices of smoked salmon, placing it on top in a wedge shape and rolling the salmon around it in a cone shape. Allow two for each person.
4. Garnish with lemon wedges and sliced cucumber and tomato. Serve with thinly sliced soda bread and butter.