once the water boils, turn the heat off and let the eggs sit in the hot water for about 15 minutes.

rinse the eggs under cold water to cool them off.

once the eggs are cool enough to handle peel them and slice in half horizontally.

scoop out the yolks and set the whites aside.

place the yolks into a food processor, add a 1/4 cup Greek yogurt, 2 teaspoons mustard; blend until the mixture is creamy.  

Using a teaspoon, scoop out the yolk mixture and drop it into each egg white. Or you can place the yolk mixture into a pastry bag, zip lock bag and cut off one corner.  Squeeze the mixture into each egg white - garnish as desired.