Wash, peel, and slice the potato into thin pieces. Steam the potato slices over high heat until tender (about 15–20 minutes). You can check by inserting a chopstick; it should go through easily.

Mash the steamed potato into a smooth paste using a spoon or masher, and let it cool completely. Measure 100g mashed potato for the dough.

In a large mixing bowl, combine 250g flour, 1 egg, 20g sugar, 3g salt, 3g yeast, 90g cold milk, and 100g mashed potato. Mix with a spatula or chopsticks until it forms a rough dough.

Knead the dough by hand until the ingredients are evenly incorporated. It will be sticky at first—this is normal.

Oil your hands and kneading surface lightly to prevent sticking, and knead the dough until smooth and elastic (about 8–10 minutes).

Add 30g softened butter to the dough. Knead until the butter is fully absorbed, and the dough becomes smooth, elastic, and can form a thin, stretchable membrane.

Place the dough in a clean bowl, cover it with plastic wrap or a damp cloth, and let it rise in a warm place for 30–60 minutes until it doubles in size.

To check if it's ready, press your finger into the dough; if the indentation stays, it's proofed.

Gently deflate the dough and divide it into 8–12 equal portions, depending on your preferred size. Personally, I like to make 9 rolls for the perfect balance of size and texture.

Take a small piece of dough, fold it a few times with your hands, then roll it into a smooth ball. Place them on a baking tray lined with parchment paper, leaving space between each roll.

Let the rolls rise for another 20–30 minutes.

While the dough is proofing, combine 30g softened butter, 2 tbsp minced garlic, and 1/4 tsp salt in a small bowl. Mix until smooth.

Transfer the garlic butter mixture into a piping bag for easier application.

Preheat your oven to 180°C (350°F). Brush the proofed rolls with beaten egg for a shiny golden crust.

Use scissors to make a small slit in the top of each roll, then pipe or spread the garlic butter into the slits. Sprinkle with chopped green onions.

Bake the rolls on the middle rack for 20 minutes or until golden brown. If the tops brown too quickly, cover loosely with aluminum foil.

Remove the rolls from the oven and let them cool on a wire rack for a few minutes. Serve warm and enjoy their heavenly aroma!