Begin by peeling and finely chopping 6 hard-boiled eggs in a mixing bowl. Use a fork to break them down into small, cohesive pieces, ensuring they are well-mixed but not pureed. This should take about 2 minutes.

Add 3-4 tablespoons of mayonnaise and 1 tablespoon of classic French mustard to your chopped eggs. Sprinkle in salt, black pepper, the minced onion, and the fresh dill. Gently fold these ingredients together with a spatula for about 2-3 minutes until everything is evenly combined.

Take 3 slices of crustless toast bread and lay them on a clean surface. Generously spread the egg salad mixture over each slice, ensuring even coverage. Place the remaining slices of toast on top to form mini sandwiches. Press down lightly to seal the layers.

With a sharp knife, slice each sandwich into bite-sized pieces, aiming for six pieces per slice. Insert toothpicks into each piece to help hold them together.

Arrange the Mini Egg Salad Sandwiches on a serving platter for immediate enjoyment or place them in an airtight container if you plan to enjoy them later. If stored, these sandwiches can be kept in the refrigerator for up to 1 day.