Remove puff pastry from freezer and let it sit out at room temperature, about 40 minutes.
Preheat oven to 400 F. Line a baking sheet with parchment paper.
Place potatoes in a medium saucepan. Cover completely with water. Bring to a boil, then reduce heat to medium low. Let simmer 10-15 minutes until fork tender. Strain.
Heat oil in a large skillet over medium heat. Add onion and cook until softened, 6-7 minutes. Add peas and carrots, and spices to skillet. Cook 3-4 minutes. Add potatoes and season with salt. Cook, stirring, another 2-3 minutes until flavors merge. Remove from heat cook slightly.
Have a small bowl of water and a pastry brush next to your work surface. On a lightly floured surface, unfold puff pastry. Cut into 9 equal rectangles.
Place about 1 tablespoon of filling in the center of each rectangle. Dip the pastry brush in the water, and wet one long side and one short side of each rectangle. Fold over like a triangle to seal in filling.
Place samosas on prepared baking sheet. Bake 15 to 20 minutes until golden brown. Transfer to a serving plate and drizzle some balsamic on top.