Japanese Egg Salad Sandwich (Tamago Sando)

Chef's Notes

Japanese Mayo: I HIGHLY recommend using Japanese mayo  – Kewpie is the most common brand that can be found at local Asian or Japanese markets. It has become increasingly popular, sometimes it’s available in the Asian aisle of grocery stores. Swapping it for American mayo will alter the flavor of the sandwich.
Bread: Shokupan, or Japanese milk bread, is a super fluffy and soft bread that’s typically used for Japanese egg sandwiches. It can be found a local Asian or Japanese markets. If you can’t find it though, you can substitute it with white sliced bread.
Unsalted Butter: I don’t recommend skipping this! Aside from the reason that butter making everything better, it also creates a barrier between the bread and egg filling so the bread doesn’t become soggy over time.
Key Tips:

Create the Creamy Filling First: To create that extra creamy texture, first mix together the egg yolks, milk, and mayo before adding the egg whites. This extra step is what creates that signature smooth and creamy filling.
Cool Filling for Easier Cutting: If you have the extra time, allow the egg mixture to chill in the fridge for about 10 minutes to firm up before adding the filling to the bread. This will make it much easier to manage when cutting.
Prevent the Filling From Drying Out: To ensure the sandwich doesn’t dry out, spread a thin layer of butter on the sides of the bread between the egg salad. This acts as a protective layer to prevent the moisture from soaking into the bread, instead of staying in the filling. It also helps ensure the bread doesn’t become soggy.