Mexican Coffee Bun

Put warm milk, 10g granulated sugar, and dry yeast into a bowl and stir slightly.

Let it sit for 5–10 minutes until fine bubbles appear on the surface.

In the bowl of a dough kneading machine/stand mixer, add flour, the remaining 70g of granulated sugar, salt, egg, and the yeast mixture (all ingredients from step 1 except butter).

Knead at medium speed for about 10 minutes (if you don't have a machine, you'll have to knead by hand), then add softened butter at room temperature and continue kneading at medium speed until a film can be formed when stretched.

Lightly flour your hands to prevent sticking, shape the dough into a round form.

Cover the dough with a lid and let it proof for the first time.

While proofing, prepare the topping: dissolve the coffee in boiling water and let it cool for later use.

Sift the flour for later use.

Mix softened butter at room temperature with the sifted powdered sugar.

Whip until the color lightens and the volume slightly increases.

Gradually add the beaten eggs in portions.

Fully whip until mixed evenly after each addition (I switched to an electric mixer later as my hand got tired).

The end result should be evenly mixed and fluffy.

Sift in the flour.

Mix until uniform.

Then add the coffee solution.

Mix again until smooth, set aside.

After about 45 minutes, the dough will have doubled to 2–2.5 times its original size.

Remove it from the bowl and knead slightly on a lightly floured surface to release most of the air.

Divide the dough into 20 equal parts (each weighing about 48–50g) and let them rest for a while.

Take one piece of dough, flatten it slightly and wrap it around 15g of red bean paste filling.

Seal the opening, place it seam-side down (I flattened them slightly) on a baking tray lined with parchment paper.

Wrap all the dough pieces in the same way; perform a second proofing. Ensure enough space between dough pieces; otherwise, they may stick together during baking.

After the second proofing for about 45 minutes, preheat the oven to 215°C.

Meanwhile, transfer the prepared coffee topping into a food-grade sealing bag (or a piping bag, if you have one, though the sealing bag works just as well). Seal the top.

Cut a small opening at the pointed end of the bag (be careful not to cut too big).

Hold the bag and pipe the topping in a spiral pattern onto the dough.

Place the buns into the preheated oven to bake for about 18 minutes (I switched the two trays midway because I was baking two at a time).

Remove the buns from the oven; once they have cooled slightly, transfer them to a rack. Avoid covering them while hot to prevent condensation. Freshly baked buns are the best—fragrant and soft.