Heat oil in a large frying pan over medium-high heat, then add in the beef mince and stir-fry until browned. Drain any excess oil, leaving approximately 1 tablespoon in the pan.
Return the pan over medium heat, then add in garlic and onion, and stir-fry for 1 minute. Add in the curry powder, turmeric, cumin, sugar, salt and pepper and stir-fry for 1 minute. Mix the cornflour with the stock in a small bowl, then pour it into the pan. Stir in the potatoes and peas, then cover the pan and cook for 5 to 6 minutes or until the potatoes have softened.
The liquid should have reduced, leaving a thick hearty curry. If there's still plenty of liquid in the pan, increase the heat to medium-high and stir continuously until the liquid reduces. Have a taste of the curry and adjust to your liking by adding more curry powder, salt or pepper to your liking if needed. Leave the curry to cool at room temperature for 10 minutes.
Preheat oven to 200°C (390°F) or 180°C (360°F) for fan-forced ovens. Line 2 large baking trays with non-stick baking/parchment paper. Follow the instructions on the packet on how to defrost the pastry sheets. Don't leave them out for too long as they'll go elastic and break easily, making them harder to work with. Cut the pastry into 4 even squares, then place 1.5 to 2 tbsp of curry filling in the centre of each square. Fold the pastries into triangles and press the edges together to seal the filling. Use a fork to crimp the edges of the pastry or fold them however you like.
Place the pastries on the tray, leaving 1.5 to 2 inches apart. Brush the top of the pastries with the beaten egg. Bake them for 25 to 30 minutes or until puffy and golden.
Notes
(NOTE 1) Beef - I used beef mince (ground beef), however, you could swap for pork, chicken, turkey or even plant-based mince.(NOTE 2) Curry powder - Any good quality curry powder will work. I've used Japanese curry powder and Keen's curry powder to make these curry puffs and they've turned out delicious. I used 2 tablespoons of curry powder because I like mine spicy and love the curry taste. However, adjust the curry to your liking, especially if you're using a hotter brand of curry powder. It's always better to start with less and adjust to your liking later.(NOTE 3) Beef stock/broth - I prefer using salt-reduced or low-sodium beef stock because I have more control over the sodium level. This way I can adjust the seasoning in dishes to my liking. It's always better to be under-seasoned than over-seasoned as it's easier to fix.(NOTE 4) Puff pastry - For convenience, I used prepackaged frozen ready-rolled pastry. Mine were 24cm (9.5in) square pastry sheets. Follow the instructions on the packet on how to defrost the pastry sheets. Don't leave them out for too long as they'll go elastic and break easily, making them harder to work with.Leftovers - Allow the Curry Puff to cool completely at room temperature, then transfer them into a sealed container and store them in the fridge for up to 3 to 4 days. When frozen, the roast beef will keep for 3 months.I've used a third-party application to calculate the calories and nutritional information, so please use this as an approximate guide only.Cooking measurements are in Australian standard spoon and cup measurements. For specific details and conversions, visit ourAustralian Cooking Measurements page.