Egg Katsu Sandwich (Tamago Sando)

Method

1. 1Peel boiled eggs; separate yolks from whites.
2. 2Mash yolks with mayo, mustard, milk, pepper and half the salt till creamy.
3. 3Chop whites into small pieces and gently mix in with chives — keep texture.
4. 4Lightly butter all four bread slices on the inside face.
5. 5Spread filling thick on two slices, top with the others, press gently.
6. 6Trim crusts, cut on the diagonal; the filling should bulge slightly when you cut.