Prepare the Filling

1. In a large pan or pot, heat a small quantity of neutral oil over medium-high heat.
2. Add the diced onion and sauté until translucent and tender. Incorporate the diced bell peppers and continue to cook for an additional 2 to 3 minutes.
3. Add the diced carrots and potatoes, followed by 2 cups of water. Once the mixture comes to a boil, stir in the vegan Japanese curry cubes.
4. Stir regularly until the cubes are fully dissolved and the curry thickens, approximately 10 to 15 minutes. For optimal filling consistency, refrigerate overnight or until the mixture becomes firm.

Prepare the Dough

1. In a large mixing bowl, combine the bread flour, all-purpose flour, corn starch, salt, sugar, and instant yeast.
2. Gradually add warm soy milk while mixing until a rough dough forms. Incorporate the neutral oil and knead by hand for approximately 8 to 10 minutes, or until a smooth, elastic dough is achieved.
3. Shape the dough into a ball and return it to the bowl. Cover with a damp cloth and allow it to proof in a warm environment for at least one hour or until doubled in size.

Assemble the Buns

1. After the dough has doubled, divide it into eight equal portions (approximately 40-45 grams each). Keep the dough covered to prevent drying.
2. On a floured surface, flatten each portion and roll into a round disc, approximately 3.5 to 4 inches in diameter. Pinch the edges of each disc to create a thinner rim.
3. Place 1 to 1.5 tablespoons of the cooled curry filling in the center of each disc. Carefully bring the edges together and seal by pinching firmly, ensuring no filling escapes.
4. Mix the soy milk and corn starch until smooth. Brush each sealed bun with the mixture. Coat evenly with panko bread crumbs.

Cooking Methods

Baking Method:

1. Preheat the oven to 350°F (175°C).
2. Place the buns on a lined baking sheet, brush lightly with oil, and bake for 35 to 40 minutes or until golden brown, flipping once halfway through if necessary.

Frying Method:

1. Heat sufficient neutral oil in a deep pan over medium-high heat (approximately 350°F or 175°C).
2. Fry the buns in batches for approximately 5 minutes on each side, or until golden brown and crisp. Ensure the oil remains at a consistent temperature.