Peel hard-boiled eggs, cut in half lengthwise, and spoon out the yolks. Place the whites cut-side up on a plate, and place the yolks in a small bowl.
Mash yolks with a fork. Add mayonnaise, honey mustard, and lemon juice; beat until smooth and fluffy. Using a mini food blender or processor works great for this step, making the filling smooth, creamy, and lump free. Mix in minced tarragon, onion, salt, and pepper.
Evenly spoon the filling into the egg whites with a teaspoon. Use a piping bag or a small plastic sandwich bag with a corner snipped off if you prefer a more decorative look.
Garnish deviled eggs with tarragon leaves, and chill in the refrigerator until ready to serve.