Toast the red pepper flakes, Sichuan peppercorns and sesame seeds in a dry skillet over medium heat until fragrant, toasted, and lightly browned, about 2 to 4 minutes.

Transfer the spices to a mortar and grind with a pestle until the peppercorns are a coarse powder, and most of the sesame seeds are crushed. Leave a quarter of them whole.

Transfer the ground spices to a heatproof bowl.

Heat the vegetable oil in a small skillet over medium heat until shimmering, hot and slightly smoking. Immediately pour over the chili peppercorn mixture.

After the sizzling dies down, let the mixture cool down for 10 minutes or more until room temperature.

Combine the sesame oil, rice vinegar, Shaoxing wine, soy sauce, sugar, garlic and ginger in a medium bowl and whisk until the sugar completely dissolves. Add to the cooled chili oil, stir and set aside until ready to use.

Put all the ingredients in a medium bowl and mix well. Stir in a circular motion until mixture is all incorporated, and has come together

If the meat mixture is too solid, add the mushroom stock 1 tbsp at a time, to loosen up the mixture and make it softer.

Fill a small bowl with water. Prepare a kitchen towel for wiping your fingers. Have your filling ready, with a parchment lined tray and damp towel to cover the wonton wrappers so they don't dry out.

Hold a wrapper in your left (or non-dominant) hand. Place 1-2 teaspoons of filling in the middle, leaving a ½ inch border on all sides. Dip your finger in the water, and run it around the edges of the wrapper. Lift and fold one corner of the wonton wrapper over the filling, meeting the opposite corner to form a triangle.

Press the air out while you seal the edges. This will ensure the meat doesn't fall out when boiling.

Dab one of the lower corners with water, and fold over to reach the other lower corner. Cross them in a hug. Pinch firmly so they stay sealed.

Bring a large pot of water to boil over high heat. Work in batches to prevent overcrowding. Cook the wontons until they float to the surface. This should take about 4-6 minutes. Take one out, and cut it to ensure the meat is thoroughly cooked. It should reach a temperature of 160 degrees. Remove with a slotted spoon.

Divide the wontons among serving bowls or a communal bowl. Drizzle with the chili oil sauce and garnish with scallions.