In a large mixing bowl, combine the beef, garlic, spring onions, pickled jalapeños and juice, soy sauce, salt, sugar, rice wine, sesame oil and fat. Stir with a wooden spoon in a clockwise direction until it resembles a thick, sticky paste – really beat the beef around the bowl to create this texture. You can incorporate a little more water if necessary. Add the sui mi ya cai and stir through. Place the mixture in the fridge while you prepare the dumpling wrappers.
If making your own dumpling wrappers: add the flour and salt to a mixing bowl and stir through with chopsticks or a fork to separate any large lumps. Add the water and quickly combine until a crumbly mixture has formed. Continue to mix until it comes together as a ball of dough. Knead for one to two minutes, then turn out onto the worktop. Continue to knead the dough (by hand or in a stand mixer) for 10 minutes or until smooth and elastic.
Mould the dough into a ball and place it inside a freezer bag, or in a bowl covered with a damp, clean dish towel. Leave to rest at room temperature while you prepare the dumpling filling. If you are preparing the dough more than one hour ahead of time, you can leave it to rest in the fridge.
Once rested, take the ball of dough and knead it for three to five minutes. Now it should feel very supple and elastic. Cut the ball into thirds, you will be working with one third at a time, so put the other two thirds back into a freezer bag or covered bowl to prevent the dough from drying out.
Roll the first dough third into a sausage shape, about 25 centimetres long. You may need to coat your worktop with a sprinkling of flour. Cut the dough into equal two centimetre pieces. Roll each piece into a ball. If you’re not using immediately, store in a container in the fridge.
To make a wrapper, take one of the small dough balls and flatten it, using three fingers, into a small disc, similar to a cookie. Roll the dough as thinly as you can, to form a round, 10 centimetres in diameter. Make sure there is a light dusting of flour on each wrapper as they are prone to sticking together. Repeat with the remaining dough, working a third at a time to stop the dough from drying out.
Take a dumpling wrapper in the palm of your hand and place one large teaspoon of filling in the centre. Bring the edges of the wrapper together and gently press the dough to seal the dumpling. You can add some pleats if you want to, but this isn’t necessary. Repeat with the remaining wrappers and place the completed dumplings on a tray lined with baking paper, at least one cm away from each other.
Mix the Chinese sesame paste with the boiling water, and stir to dissolve. To each serving bowl, add two tablespoons of the Chinese sesame paste mixture (this should still be warm from the boiling water), one to two tablespoons chilli oil (to taste), one tablespoon pickle juice and ½ teaspoon sugar. Mix well to combine, until the sugar is dissolved.
Heat the neutral oil in a non-stick frying pan over a medium heat, and boil the kettle. Add some dumplings to the pan – they will need at least one cm between them, so you may need to cook them in batches. After three to four minutes, the bottoms of the dumplings will become brown and crisp.
Add enough boiling water to fill the pan to a depth of about one centimetre. This will create a burst of steam, so make sure your face is a safe distance away! Put a lid on the pan and leave the dumplings to steam for six to eight minutes or until all the water has evaporated. Remove the lid and let the dumplings fry on the bottom of the pan for another minute or two, then remove from the heat and allow to cool slightly – this will loosen them from the pan and make them easier to scoop out.
Serve the dumplings in the sauce, crispy side up. Top with sesame seeds, chives and a pinch of ground Sichuan pepper.