1/2 kg prawns, shelled and drained  
1 egg  
2 tbsp white vinegar  
1 tsp grated lemon rind  
2 tsps lemon juice  
2 tsps tomato sauce  
salt to taste  
1/2 cup refined oil
1. Heat the butter and fry prawns in it till brown.
2. Mix the egg yolk, vinegar, lemon rind and juice, and tomato sauce and heat well.  Add the prawns.
3. Put the mixture in a blender and liquidise.  Add the oil gradually while the blender is operating.  Blend till the mixture is smooth the thick.
4. Serve with cutlets, or as dressing for any salad.