Begin by halving the Roma tomatoes and scooping out their seeds to prevent a soggy filling. Dice the remaining tomato flesh into ½ cm pieces and set aside.

Slice the green onions thinly, using only the white parts for optimal texture and a milder flavor. Add them to the diced tomatoes in a mixing bowl.

Finely shred the butter lettuce and add it to the bowl with the tomatoes and onions. Meanwhile, mash the hard-boiled eggs in a separate bowl.

In the bowl with the mashed eggs, incorporate the diced tomatoes, chopped green onions, and shredded lettuce. Mix gently until everything is well combined. Add mayonnaise to bind the mixture.

Take two slices of bread and butter the inner surfaces generously.

Spread the egg salad filling evenly on one buttered side of each pair of bread slices.

Using a sharp knife, cut off the crusts from each sandwich to create neat edges. Then, slice each sandwich into quarters.

Arrange the quartered sandwiches on a platter, optionally serving them alongside crisps for added crunch.