Slice the boiled eggs in two halves and scoop the yolks out. Put all the egg whites on a plate and all the egg yolks in a small mixing bowl.
Mash the egg yolks into a smooth paste, using a fork. Next, add mayo or Greek yogurt, lemon juice, mustard sauce, garlic powder, salt, and pepper to the yolk paste and mix everything well.
Start filling the egg whites with the yolk filling, using a spoon or a piping bag.
Sprinkle parsley and herbs mix on top of the filling. Serve immediately with toasted whole-grain bread or saucy pasta.