Halve the eggs lengthwise and place whites on to a serving plate or into whatever you plan to store them in. Place the yolks into the mixing bowl.
To start, add 2 ½ Tbl of mayo, 1 teaspoon mustard, and pepper to yolks. Attach whisk attachment to mixer and start to whisk the yolks at medium speed. Gradually increase the speed and add mayo tablespoon by tablespoon. Stop the mixer and scrape down the sides. Taste to see if more want to add additional mustard to you filling. Gradually increase speed to high and if you need to add more mayo add it slowly. The mixture will become fluffy and smooth, the color will lighten, and there will not be lumps. If the filling is thick and lumpy slowly add more mayo. Once desired consistency is achieved, season with salt.
Using a spatula, put the yolk filling in a gallon bag and push it towards one corner. Cut the tip from the corner and pipe the filling into the egg whites. Sprinkle with paprika if desired.