For the chicken:
Place the chicken breasts in a deep-sided saucepan in the water and sherry with the onion, bay leaves and seasoning.
Poach at a gentle simmer for 20 minutes (taking care not to overcook).
Cool in the liquid, then remove (reserving 3T of the poaching liquid for the dressing) and slice lengthwise into long, thin strips.
For the dressing:
Place all the ingredients in a glass bowl and whisk over a pot of boiling water, taking care not to allow the bottom of the bowl to touch the water.
Whisk for about 15 to 20 minutes until dressing is smooth and slightly thickened (it should easily coat the back of a spoon).
To assemble the dish:
Check seasoning and pour dressing, while still warm, over the sliced poached chicken.
The dressing will thicken as it cools. When cool, cover and refrigerate.
To serve, place the chicken down the centre of a serving platter and scatter butter lettuce leaves all around the chicken. Sprinkle with paprika and toasted almonds.