Ingredients

Check off ingredients as you go

  • Eggs (large, for half-boiling) 2 eggs

    Approx. 110 g without shell, for the jammy center

  • Water as needed

    For boiling eggs

  • Ice water for cooling

    To stop cooking and cool eggs quickly

  • Eggs (large, for hard-boiling) 3 eggs

    Approx. 165 g without shell, for the filling

  • Regular mayonnaise 75 g

    Full-fat, neutral mayo for best mouthfeel

  • Yellow mustard (mild) 5 g

    For depth, not sharpness - use mild variety

  • Salt 2 g

    For seasoning the filling

  • White pepper 0.5 g

    For subtle warmth without visible specks

  • Sugar (optional) 1 g

    Very subtle sweetness, optional

  • Soft white milk bread 4 slices

    Shokupan-style, approx. 120 g, crusts removed

  • Unsalted butter, softened 20 g

    For spreading on bread slices

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Instructions

  1. Prepare the Half-Boiled Eggs
    • Bring a saucepan of water to a gentle boil
    • Carefully add 2 eggs
    • Cook for 6½ minutes for a jammy, custard-like yolk
    • Immediately transfer to ice water and cool completely
    • Peel gently and set aside
  2. Prepare the Hard-Boiled Eggs for Filling
    • Boil 3 eggs for 10 minutes
    • Transfer to ice water, cool completely, and peel
  3. Make the Egg Mayo Filling
    • Separate yolks and whites from the hard-boiled eggs
    • Finely mash the yolks until completely smooth
    • Add mayonnaise (75 g), mustard (5 g), salt (2 g), white pepper (0.5 g), and sugar (1 g, if using)
    • Mix until creamy, pale, and glossy
    • Finely chop the egg whites and gently fold them into the yolk mixture
    • The filling should be smooth, rich, and easily spreadable
  4. Prepare the Bread
    • Trim crusts from all bread slices for a clean finish and soft bite
    • Lightly butter one side of each slice with softened butter (10 g per sandwich)
  5. Assemble the Sandwich
    • Spread a generous, even layer of egg mayo filling on one buttered slice
    • Place one half-boiled egg horizontally in the centre
    • Spoon more egg mayo filling around and over the egg, filling all gaps evenly
    • Top with the second slice of bread, buttered side facing inward
    • Press gently to set
  6. Rest and Slice
    • Wrap the sandwich tightly in parchment or cling film
    • Rest for 5–10 minutes to allow the filling to settle
    • Slice cleanly through the centre to reveal the jammy yolk

Chef's Tips

Mustard Control

Keep mustard mild and measured — it should add depth, not sharpness. Yellow mustard works best for its subtle flavor.

Texture Is Everything

Yolks must be fully smooth; whites finely chopped, never mashed. This creates the perfect creamy yet textured filling.

Mayo Choice Matters

Use a full-fat, neutral mayo (like Japanese Kewpie or similar) for the best mouthfeel. Avoid strongly flavored mayonnaises.

Serving Temperature

Best served slightly chilled or at cool room temperature. This allows the flavors to meld and makes for cleaner slicing.

Presentation Perfection

Clean cuts and visible yolk are part of the charm — use a sharp, serrated knife dipped in hot water for perfect slices.

Egg Timing Precision

6½ minutes for half-boiled eggs gives the perfect jammy center. Use a timer for consistent results every time.

Bread Selection

Authentic Shokupan (Japanese milk bread) is ideal, but any soft, pillowy white bread with minimal crust works well.

Video Tutorial

Watch step-by-step on Instagram

Tag: @japanesecookinglab