Heat the vegetable oil in a large frying pan and saute the onions and garlic and a tablespoon of the curry powder in the oil until the onions begin to sweat.
Next, add the beef, soy sauce, fish sauce, and the remaining curry powder. Stir everything together, brown the beef, and allow the mixture to cook for another couple of minutes.
Adjust the taste with salt and white pepper.
Take the sheets of puff pastry out of the freezer and let them defrost. Take one piece of puff pastry, flatten it using a rolling pin, and cut it into nine rectangles.
Put a generous tablespoonful of the meat mixture into one side of each rectangle and then brush the edges with egg white. Fold it over to close it and press the edges completely shut. Crimp the edges with a fork and transfer to a baking sheet or baking tray.
When ready to bake, brush with egg wash (egg yolk) and bake in a preheated oven at 400F for 18-20 minutes or until golden brown.