Steps

1. Trim the ends off 1.5 cucumbers (approx. 180g). Use the back of your knife to remove any bumps from the surface, then thinly slice them into 7mm thick pieces. (Tip: Slicing with a knife instead of a mandoline creates irregular shapes that add a textural accent.)
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2. Add 1/4 tsp salt to the sliced cucumbers and rub them together. Let sit for 10 minutes.
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3. In a bowl, combine 1 tbsp mayonnaise, 2/3 tsp miso, 1/3 tsp sugar, and a pinch of ground mustard. Mix well.
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4. Wrap the cucumbers from step 2 in a clean kitchen cloth and squeeze out the moisture thoroughly. (Tip: Squeeze out as much water as possible to prevent the bread from getting soggy.)
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5. Add the squeezed cucumbers to the mixed seasonings and combine everything.
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6. Spread margarine (amount as needed) generously on one side of 2 slices of shokupan (6-slice thickness). Then, spread the cucumber and seasoning mixture over the margarine. (Tip: Applying margarine to the bread prevents the cucumber moisture from soaking into it.)
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7. Place the bread with the cucumber filling on top of the other slice of bread, place a weight on top, and let it rest in the refrigerator for 5 minutes.
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8. After 5 minutes, trim off the crusts.
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9. Cut the bread crosswise into four equal pieces.
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