If using raw walnut pieces, preheat your oven to 180°C (356°F). Roast the walnuts for 10-15 minutes until they are lightly golden and fragrant. Once roasted, allow them to cool slightly, then rub off the outer skin as much as possible. Chop the walnuts into coarse pieces—aim for a mix of sizes for a better texture.

If starting with raw black sesame seeds, heat a dry skillet over medium heat. Add the sesame seeds and toast them, stirring frequently, until they crackle and turn darker in color and aromatic. This should take about 5-7 minutes.

In a large bowl, combine the chopped walnuts, toasted black sesame seeds, condensed milk, brown sugar, and lard. Mix thoroughly with chopsticks or a spoon until you have a sticky filling. Set this mixture aside for later use.

In a large mixing bowl, combine 120 grams of brown sugar with 230 grams of hot water. Stir until the sugar has completely dissolved.

Allow the sugar water to cool to a lukewarm temperature, then sprinkle in the 5 grams of high-sugar tolerant yeast. Stir gently to ensure the yeast dissolves fully.

Gradually add 500 grams of all-purpose flour to the yeast mixture while continuously stirring with chopsticks or a whisk. Continue mixing until the flour absorbs the liquid and forms a shaggy dough.

Once the mixture starts to come together, transfer the dough to a clean work surface. Knead the dough for about 10-15 minutes until it becomes smooth and elastic. If the dough feels too dry, add a little water; if too wet, add a sprinkle of flour. This step is essential for developing gluten, which will give the buns their delightful texture.

Divide the dough into equal portions, approximately 35 grams each. You can roll the dough into a long log and cut it into pieces for uniformity.

Take one piece of dough and flatten it into a round disc using your palm. Ensure the thickness is even for proper cooking.

Spoon a generous amount of the walnut filling into the center of the dough disc. Be careful not to overfill, as this can cause the buns to burst during steaming.

Pinch the edges of the disc together, gathering the dough around the filling to seal it securely. You want to ensure there are no gaps for the filling to escape.

Use a spatula to gently press down in the middle of the bun, creating a shallow indentation. This indentation will help hold the shape better during the subsequent shaping process.

If you have a walnut-shaped mold, use the mold to press out the shape of the walnut.

Line your steamer with parchment paper or lightly oil it to prevent sticking. Place the shaped buns on the steamer, leaving enough space between each bun to allow for expansion.

Cover the steamer with a lid and allow the buns to proof in a warm, humid environment for 30-60 minutes. You can create a warm atmosphere by placing a bowl of warm water inside the steamer or keeping it in a warm room. The buns should roughly double in size.

After proofing, bring water to a boil in your steamer. Once the water is boiling, carefully place the steamer basket over the boiling water.

Steam the buns for about 12 minutes on high heat. It's essential to maintain a steady boil to ensure proper cooking.

After 12 minutes, turn off the heat but do not open the lid immediately. Allow the buns to rest in the steamer for 3-5 minutes. This resting time helps maintain their shape and prevents them from collapsing due to sudden temperature changes.