Slice the hard-boiled eggs in half lengthwise. Scoop out the egg yolks and transfer them to a small mixing bowl*.
Using a fork, mash the egg yolks completely until they form a fine powder. Add in the Greek yogurt (or mayo), lemon juice, Dijon, and a generous pinch of salt and pepper and stir until completely combined. Taste the mixture and season with extra salt and pepper, if needed. Or if the mixture seems too thick, just add in some more Greek yogurt or a tiny splash of water.
Either using a spoon or a small cookie scoop or a piping bag, fill the inside of the egg whites with the yolk mixture. Sprinkle each deviled egg with a generous pinch of everything bagel seasoning. Then serve and enjoy immediately!
Notes
*For a super-smooth egg yolk filling, you can alternately add the yolks, Greek yogurt (or mayo), lemon juice, Dijon, salt and pepper to a food processor and pulse until completely smooth.