In a large mixing bowl, combine 500g flour and 3g salt. Slowly add 280g water while stirring the flour mixture with chopsticks or a whisk until it forms a shaggy dough.

Transfer the dough to a work surface and knead it by hand. Continue kneading vigorously for about 10 minutes, folding and pressing the dough until it becomes smooth and elastic.

Divide the dough into 10 equal portions, roll each portion into a long strip, and place them in a container. Lightly spray the surface of the dough pieces with vegetable oil.

Cover the container with plastic wrap and refrigerate overnight. This resting time improves the dough's stretchability and makes it easier to work with.

Clean 400g beef tenderloin and cut it into small chunks. Mince the beef by hand or use a food processor, making sure to leave some texture for a better mouthfeel.

Place the minced beef in a bowl and add 50g Sichuan pepper water. Mix thoroughly with your hands to allow the beef to absorb the liquid, which enhances its tenderness and removes any gamey flavor.

Next, add 15g light soy sauce, 5g dark soy sauce, 10g oyster sauce, 2g salt, and 2g chicken bouillon powder to the beef mixture. Stir well to combine the seasonings evenly throughout the meat.

Crack 1 egg into the mixture and stir until fully incorporated.

Finally, pour in 30g vegetable oil and mix until the filling is smooth and slightly glossy. Set aside.

In a small bowl, mix 30g flour with 2 tsp salt and pepper powder.

Heat 30g vegetable oil in a small pan until it begins to smoke lightly. Pour the hot oil into the flour mixture and stir quickly to form a smooth, paste-like consistency. Set aside to cool slightly.

Remove the dough from the refrigerator and let it rest until it reaches room temperature.

Take one portion of dough and roll it out into a rectangular sheet about 2-3mm thick. Ensure the dough is evenly rolled out to avoid thick or thin spots.

Spread a thin layer of the prepared oil paste evenly across the surface of the dough sheet.

At one end of the dough, place a generous amount of the beef filling and sprinkle with chopped green onions. Adjust the amount of filling to your preference, but avoid overfilling to prevent spillage during rolling.

Starting from the filling end, gently roll the dough into a log shape. Pull the dough slightly as you roll to make it thinner, which will help the crust become crispier. Seal the edges tightly to fully enclose the filling.

Press the rolled dough log flat with your hands to form a round pie shape. Sprinkle black sesame seeds on the top and press them into the dough to help them stick.

Using an electric griddle: Preheat the griddle and select the meat pie setting. Lightly spray the cooking surface with vegetable oil to prevent sticking. Place the prepared pies on the griddle, close the lid, and let them cook for 5-8 minutes. The griddle will automatically control the temperature and time. The pies are ready when they're golden brown and crispy on the outside and fully cooked inside.

Using a frying pan: Heat a large frying pan over medium heat and add a thin layer of vegetable oil. Place the meat pies in the pan and fry over low heat, flipping occasionally to ensure even cooking on both sides. Fry for 8-12 minutes until the crust is golden brown and the filling is cooked through. Be patient and use low heat to avoid burning the crust before the inside is done.