Heat oil in wok, add in curry leaves and onion. Stir-fry onion until translucent, then add in potato. Cook until potato has changed colour on the edges and then add in curry powder and chili paste (optional).
Cook for 1 minute, add in water and bring to boil.
Add salt to taste, then turn the heat down and cook with lid on until potato is soften and the liquid is reduced. Cool completely before use.
NOTE: If you are not vegan, you can add shrimp or chicken or ground beef or lamb. You can add/remove the amounts of the filling ingredients and tweak it to suit your taste. Only the pastry ingredients should remains as is.
In a large mixing bowl, bring 3 types of flours together and mix well. Set aside.
In a small sauce pan, melt and heat butter with oil.
Pour hot oil over flours in the mixing bowl. Then, mix thoroughly with a wooden spatula or chopsticks. Add in water and knead to form soft dough. Cover dough with plastic wrap and rest for at least 15 minutes.
Assemble: Divide and shape dough into 24 equal balls. Then roll out each ball into an 8 to 10 cm circle, wrap in a heap tablespoon filling. Pinch edges to seal, then deep-fry in medium hot oil until golden brown.
Serve warm or at room temperature.