In a large bowl, mix the flour and salt. Add the cold butter and use a pastry cutter or your fingers to blend until the mixture resembles coarse crumbs.

In a small bowl, combine the cold water and vinegar. Gradually add this to the flour mixture, stirring until the dough comes together. Knead gently for a minute, then wrap in plastic wrap and refrigerate for at least 30 minutes.

For the filling, heat the vegetable oil in a skillet over medium heat. Add the onion, garlic, and ginger, cooking until the onion is translucent.

Add the ground chicken (or turkey) and cook until browned. Stir in the diced potatoes, curry powder, turmeric, salt, and black pepper. Cook for about 10 minutes, or until the potatoes are tender.

Stir in the peas and soy sauce, cooking for an additional 2 minutes. Remove from heat and let the filling cool.

Preheat your oven to 400°F (200°C).

On a floured surface, roll out the chilled dough to about 1/8 inch thick. Cut into 4-inch circles.

Place a tablespoon of filling in the center of each circle. Fold the dough over to create a half-moon shape and crimp the edges to seal.

Place the curry puffs on a baking sheet lined with parchment paper. Brush the tops with vegetable oil.

Bake for 25-30 minutes, or until golden brown. Serve warm.