Bring water to a boil in a pot.
Add the egg and boil for 6-9 minutes (depending on the size and how runny egg yolk you prefer. When making a sandwich I prefer it more set).
Meanwhile combine the ingredients for the tuna salad in a bowl and the ingredients for the hot smoked salmon salad in another one.
Preheat a nonstick pan and add the whole grain bread to warm it up and let it become a little golden brown. You can also use a bread roaster or the oven. This is optional, but it really makes the sandwich more delicious.
When the egg is done drain it under cold water for 1-2 minutes.
Peel and slice the egg.
Place salad leaves on each bread slice.
Top two of the bread slices with tuna salad, sliced egg and capers.
Top the other two bread slices with salmon salad, thinly sliced radish and sunflower sprouts.