Preheat the oven to 375 degrees F (190 degrees C).

Mix all-purpose flour, pastry flour, and salt in a bowl, add vegetable oil while stirring, and gradually add ice-cold water until dough forms. Shape into a ball and cover.

Boil peeled potatoes in salted water, drain, and mash with small chunks remaining.

Mix mustard seeds, curry powder, ginger, cumin, and red pepper flakes in a bowl.

Heat vegetable oil in a skillet, cook onion, carrot, and garlic until tender.

Toast spices in the skillet, then mix them with the cooked vegetables. Add vegetable broth and peas.

Fold the seasoned mixture into the mashed potatoes, add sugar, salt, and pepper. Spread into a pie plate.

Roll out the dough into an 11-inch circle, place over the filling, seal edges, vent steam, and brush with milk.