Uguisu-pan (うぐいすパン, green-pea-paste bun)

Ingredients

Equipment Needed

• •Uragoshi (fine Japanese sieve), or a sturdy fine-mesh strainer
• •Stand mixer with dough hook, or a clean counter and bench scraper
• •Kitchen scale
• •Rimmed baking sheet lined with parchment

Instructions

1. 1

   Make the yudane

   Put 50g bread flour in a heatproof bowl. Pour in the boiling water and stir until it becomes a thick, slightly translucent paste. Cover it and let it cool to room temperature, about 30 minutes. This is yudane, scalded flour; it gelatinizes some starch so the finished crumb stays soft without making the dough sloppy.

2. 2

   Blanch the peas

   Bring a pot of water to a boil and add a pinch of salt. Add the peas and cook until tender enough to crush between your fingers, 3 to 5 minutes for fresh peas or 2 to 3 minutes for frozen. Lift them straight into ice water. The cold stop keeps the green clear and prevents the pea flavor from turning dull.

   Do not undercook the peas for color alone. A hard pea makes a gritty paste, and no amount of sieving will make it gentle.
3. 3

   Pass the peas

   Drain the peas very well, then puree them until smooth. Press the puree through an uragoshi, a fine Japanese sieve, or a sturdy fine-mesh strainer, scraping the underside as you work. The skins are small, but they catch on the tongue and make the filling feel coarse; removing them is what makes uguisu-an gentle.

4. 4

   Cook the uguisu-an

   Put the pea puree in a wide saucepan with the sugar, salt, and mizuame if using. Cook over medium-low heat, stirring constantly with a spatula, until the paste thickens, pulls from the sides, and a line drawn across the bottom of the pan holds for several seconds, 10 to 15 minutes. It will firm more as it cools, but it must already mound on the spoon. A wet filling leaks into the dough and makes a heavy ring around the paste. Spread it on a tray, cool completely, then divide it into 12 balls.

5. 5

   Mix the dough

   Tear the cooled yudane into small pieces. In the bowl of a stand mixer, or in a mixing bowl, combine the remaining bread flour, sugar, yeast, and salt. Add the lukewarm milk, beaten egg, and yudane, then mix until a shaggy dough forms. The pieces of yudane look untidy at first; keep mixing and they disappear, giving moisture without looseness.

6. 6

   Knead in butter

   Knead for 5 minutes, then add the softened butter piece by piece and knead 6 to 8 minutes more, until the dough is smooth, elastic, and slightly tacky. A small piece should stretch thin before it tears. Add the butter after the dough has some strength, so the fat coats an organized dough instead of greasing loose flour and slowing the structure.

7. 7

   Let it rise

   Shape the dough into a ball, set it in a lightly oiled bowl, cover it, and let it rise in a warm place until doubled, 60 to 75 minutes. Press a floured finger into the dough; the dent should remain without the dough collapsing. Underproofed dough fights shaping, while overproofed dough loses spring and opens at the seams.

8. 8

   Divide and rest

   Turn the dough onto the counter and divide it into 12 equal pieces, about 55g each. Shape each piece into a round, cover, and rest for 15 minutes. Rest is not idleness. It relaxes the gluten so the dough stretches around the filling instead of snapping back.

9. 9

   Fill the buns

   Flatten one round into a 9cm disk, leaving the center slightly thicker than the edges. Set one ball of uguisu-an in the center, bring the dough edges up around it, and pinch the seam firmly closed. Place it seam-side down and repeat. The thicker center protects the top from tearing, and the thinner edges close without making a lump underneath.

10. 10

    Proof the buns

    Set the buns seam-side down on a parchment-lined baking sheet, leaving space between them. Cover and proof 35 to 45 minutes, until puffy but not fragile; a fingertip pressed into the side should slowly spring back. Stop there. If they balloon, the seams open and the filling wanders.

11. 11

    Glaze and bake

    Heat the oven to 180C (350F). Beat the egg yolk with 1 teaspoon milk and brush the tops lightly, taking care not to flood the seams. Sprinkle with white sesame seeds. Bake 14 to 16 minutes, until honey-gold and the underside sounds dry when tapped. Cool at least 20 minutes before eating. The crumb finishes setting as it cools, and hot uguisu-an is a small lesson in patience.

Chef Tips

• •Fresh shelling peas are the shun choice: pods should be plump, glossy, and heavy, with peas that smell sweet when you open them. Out of season, frozen petite peas are better than tired fresh peas because they were caught young.
• •Do not fix the color with food dye. If the peas cook to a softer green, let them. Uguisu color is a spring hint, not a paint chip, and honmono has room for quiet color.
• •Cook the paste farther than feels comfortable: it should stand in a mound and leave the pan clean for a breath. The bun fails from wet filling far more often than from imperfect shaping.
• •Keep the dough tacky. Extra bench flour feels helpful for ten seconds, then gives you a dry bun. Oil your fingertips lightly if the dough clings.

Advance Preparation

• •Uguisu-an can be made up to 2 days ahead and refrigerated. Roll it into balls while cold; cold filling behaves.
• •The yudane can be made the night before and refrigerated. Bring it back to room temperature before mixing so it doesn't chill the dough.
• •The dough can rise overnight in the refrigerator after kneading. Let it stand at room temperature for 30 to 40 minutes before dividing and shaping.
• •Baked buns keep 2 days well wrapped at room temperature, or 1 month frozen. Refresh thawed buns in a 150C (300F) oven for 6 to 8 minutes.

Frequently Asked Questions

Nutrition Information

1 serving (about 105g)