Step 1: Hard-boil the eggs. Place eggs in a single layer in a saucepan and cover with cold water by about an inch. Bring the water to a rolling boil over high heat. Once boiling, immediately turn off the heat, cover the pan, and let the eggs sit in the hot water for 10-12 minutes for firm yolks.
Step 2: Prepare an ice bath. Fill a large bowl with ice and cold water. Carefully transfer the hot eggs to the ice bath and let them cool completely for at least 15 minutes.
Step 3: Once cooled, gently tap each egg on a hard surface to crack the shell all over, then peel them under cool running water. Discard the shells.
Step 4: Roughly chop the peeled eggs. You can use a knife, a pastry blender, or a potato masher, depending on your preferred texture.
Step 5: In a medium-sized mixing bowl, combine the chopped eggs with mayonnaise, Dijon mustard, finely chopped celery (if using), and fresh dill or chives. Season generously with salt and freshly ground black pepper.
Step 6: Gently mix all the ingredients until just combined. Be careful not to overmix. Taste and adjust any seasonings as needed.
Step 7: Cover the bowl and refrigerate the egg salad for at least 30 minutes to allow the flavors to meld. Store any leftovers in an airtight container for up to 3-4 days.
Step 8: To assemble, spread a generous amount of the chilled egg salad onto your favorite bread. Garnish with a sprinkle of paprika, extra fresh dill, or a slice of tomato if desired. Serve immediately.