Preheat your oven to 200°C (390°F). Line a baking sheet with parchment paper to prevent sticking and set aside.
In a dry skillet over medium heat, toast the cumin seeds until fragrant, about 30 seconds. This releases their smoky aroma and enhances the filling's flavor.
Add the mashed potatoes, frozen peas, turmeric, curry powder, and a pinch of salt to the skillet. Stir everything together and cook for about 3-4 minutes until heated through and fragrant. Remove from heat and stir in the lemon juice for a fresh, zesty kick.
Meanwhile, prepare the dough by mixing the flour, salt, and olive oil in a bowl. Gradually add water and knead until the dough is smooth and elastic, about 5 minutes. Cover with a damp cloth and let rest for 15 minutes to relax the gluten.
Divide the rested dough into 8 equal portions. Roll each piece into a thin circle about 15 cm (6 inches) in diameter on a lightly floured surface. Use a rolling pin to achieve an even thickness.
Scoop about 2 tablespoons of the filling onto one side of each dough circle. Moisten the edge with a little water using the small brush or your finger, then fold the dough over to form a semi-circle.
Press along the sealed edge and crimp with your fingers or a fork to create a tight seal, ensuring no filling escapes during baking.
Place the assembled samosas on the prepared baking sheet. Brush the tops lightly with olive oil for a golden, crispy finish.
Bake in the preheated oven for 20-25 minutes, turning the tray halfway through, until the samosas are deep golden brown and crispy. Keep an eye on them after 15 minutes to prevent over-browning.
Remove the samosas from the oven and let them rest for 5 minutes. Serve warm with your favorite chutney or yogurt for dipping and enjoy the satisfying crunch.
