SALMON: Generously season the salmon fillet on both sides with the salt and pepper. Place the salmon in an 8-inch skillet. Add water and lemon juice. Bring the water to a simmer over high heat. Reduce the heat to low, tightly cover the pan and poach salmon until medium-rare (5-6 minutes). Remove pan from heat. Allow salmon to cool to room temperature in liquid with the lid on.
Remove the salmon from the liquid and break it apart with your fingers into small pieces. In a medium bowl, combine the poached salmon, smoked salmon and mayonnaise. Mix well. Store tightly covered in the refrigerator. Serve cool, but not cold. Makes about two cups.
MAYONNAISE: In a blender, combine the egg yolk, lemon juice and mustard and blend until well mixed. With the machine running, add olive oil, at first by drops and then, as the mixture emulsifies, in a thin, steady stream until all the oil is incorporated. Add the remaining mayonnaise ingredients and blend. Taste for seasoning. Scrape into a jar, cover and refrigerate until needed (will keep for 2-3 days in refrigerator).