Poach the chicken or turkey breasts in 2 litres of simmering water for 10 – 15 minutes. Remove from water and strain. When cool, cut into pieces and pulse in the food processor until roughly chopped.
Place chicken in a bowl with remaining ingredients.
Combine well and season to taste.
Lightly spread the butter over each slice of bread.  Spoon mixture onto buttered side and top with another.  Remove crusts and wrap in plastic wrap.  Refrigerate until ready to use. Cut just before serving.

Tip: For extra flavour, poach the chicken in 1.75 litres water combined with 250ml dry white wine, a bouquet garni and six whole black peppercorns.  You can also add a small bulb of finely diced fennel and the leaves from a bunch of chervil (roughly chopped) to the sandwich filling, if liked. Chopped fresh pistachios are also a nice addition.

Melt the butter and sweat the onion and potato for 3 – 4 minutes over medium heat, stirring occasionally. Add the stock, bring to the boil and simmer 15 – 20 minutes or until potatoes are soft.
Remove from heat and pour into a blender.  Liquidise the soup base, adding the green leaves and herbs halfway through – this ensures a vibrant colour.  Season to taste.  Serve hot or cold garnished with basil or watercress.

Tip: when sweating vegetables, make sure to add a pinch of salt (to release the juices) and to cover them with a lid.  Add  1/2 cup milk or cream for a creamier soup, if liked.