In a small saucepan, whisk together the water, milk, and flour. Cook over medium heat, stirring constantly, until it thickens into a smooth, glossy paste. Remove from the heat and let it cool completely before using.

Warm the milk until just lukewarm, then mix in 1 tsp sugar and the yeast. Let it stand for 5–10 minutes until foamy and activated.

In a mixing bowl, combine the yeast mixture with the cooled tangzhong, egg, sugar, salt, and flour. Mix until the dough starts to come together. Add the softened butter and knead for 8–10 minutes until the dough becomes smooth, elastic, and only slightly tacky.

Cover the bowl and let the dough rise in a cool room for 1–2 hours, or until doubled in size.

Punch out the air and divide the dough into 9–10 equal pieces. Shape each portion into a smooth ball and rest them for 10 minutes. Roll each ball into an oval or triangle shape, place a 10 g stick of butter at the wide end, and roll it up like a small croissant, making sure the tip is on the bottom.

Arrange the rolled salt breads on a lined baking tray, tip-side down. Cover lightly and let them rise again for 30–40 minutes until noticeably puffy.

Lightly mist the tops with water (this helps with oven spring). Bake for 5 minutes at 200°C (392°F), then lower to 180°C (356°F) and bake for another 10–13 minutes until golden.

Brush immediately with garlic butter or plain melted butter. Serve warm, the inside will be fluffy with a perfectly melty butter core.