Combine the flour, water, salt, and oil. Knead into a rough dough. Make sure all the flour is hydrated. If the dough feels dry, add water, one teaspoon at a time. You should be able to form a rough dough. Cover and let the dough rest for 2 hours
Prepare the filling: (can be prepared the day before)
Add the beef into a large mixing bowl. Add 1/4 cup of the water and stir to work the water into the beef, then add another 1/4 cup and mix until the beef is moist
Add all the seasonings. Do not cut down on the black and white peppers. I know it seems a lot, but it will work out. Add the green onion and diced onion. Use a chopstick to stir in one direction until you form a sticky meat paste. Divide the meat filling into 8 portions. Cover and set aside.
Back to the dough:
Lightly dust your work surface with some flour. Put the dough on the work surface. Don't knead it. Just gently roll it into a log, about 10-12 inches long. It doesn't have to be exact. Cut into roughly 8 equal pieces. 10 pieces if you want smaller pies
Round the dough up into balls. Keep them covered and work with one dough at a time. Use a rolling pin to roll into a circle, about 6 inches, with the center thicker than the edge to support the weight of the filling
Wrapping:
Put one portion of the meat filling and put it on the center of the wrap. Fold the edges to create a pleat to close the wrap while pushing the filling down with your thumb. Take care not to let the filling touch the edge of the dough because the dough gets slippery and it's hard to pinch it to seal. Pinch the dough seal to shut. If you don't know how to pleat the wrapper, simply gather the edge towards the center and pinch it to seal it. Place it seam side down and flatten the dough slightly with your palm. Repeat with the rest of the dough and the filling
If not cooking on the same day:
You can make ahead up to this point. If not cooking right away, you need to keep them in the freezer, NOT in the fridge as the dough will get wet and sticky
Place the uncooked meat pies on a baking pan lined with parchment paper and put them in the freezer for about 1 hour. They won't be completely frozen yet but they won't stick to each other anymore. Transfer them to an air-tight container or freezer-friendly bag, push all the air out and seal. They can be kept frozen for 1 month
Pan frying the pies:
Preheat a large pan with oil. When the oil is hot, arrange the pies on the hot pan. Try not to overcrowd and cook in batches if necessary. Let them cook for about 3 minutes on one side over medium-high heat. Then flip to the other side, cover and cook for another 3 minutes over medium-high heat. Then turn down the heat to low and cook for another 5 minutes on each side to ensure the meat filling is cooked through. The crust should have nice golden brown color
Place them on absorbent paper towel to absorb any excess oil
If you have kept the uncooked pies previously frozen, don't thaw. You can cook them frozen, but just need a few extra minutes
Serving:
Serve immediately when they are still warm and crispy
How to store leftovers:
Keep them in an air-tight container and keep them in the fridge for about 3-4 days. Simply reheat on the pan until heated through. You can also reheat in the microwave in a 10-second increment until the pies are heated through