To make the filling, in a bowl, combine the ground chicken with the chicken stock and mix until the liquid is fully absorbed, then add the soy sauce, dark soy sauce, white pepper, sesame oil, and egg and mix well. Then, add the shiitake mushrooms and scallions and mix until evenly combined.
To fill and fold, place a wrapper in your hand, add about 1 teaspoon of filling in the center, top with a piece of asparagus, lightly brush water along the edges, fold in half, and press to seal.
To pan-fry, in a pan over medium heat, add the cooking oil and place the potstickers flat-side down and cook for about 1 minute until the bottoms are lightly golden.
To steam, carefully add the water to the pan and cover with a lid and cook for about 7 minutes until the filling is cooked through and most of the water has evaporated.
To crisp, remove the lid and let any remaining water cook off, allowing the bottoms to crisp up again.
To make the dipping sauce and serve, in a bowl, mix the soy sauce, vinegar, and chili oil, then serve the potstickers hot with the dipping sauce.