Begin by mashing the peeled hard-boiled eggs in a medium-sized bowl until they reach your desired consistency. Stir in the yellow mustard and mayonnaise, mixing thoroughly. Season the mixture with salt and pepper, and adjust according to your taste preference.

Once the egg salad is ready, spread a generous spoonful onto a slice of bread, then place another slice on top to create a sandwich. Repeat this process for the remaining bread and egg salad, yielding approximately four sandwiches.

For a fresher bite, you can add lettuce to your sandwich. Store any leftover egg salad in an airtight container in the refrigerator for up to 5 days, depending on the freshness of the eggs.