In a large bowl, combine 2 cups of all-purpose flour, a pinch of salt, and a pinch of baking soda. Add 2 tablespoons of oil and mix with your fingertips until the mixture resembles coarse breadcrumbs. Gradually add warm water and knead until you have a smooth, soft dough. Cover with a damp cloth and let it rest for at least 30 minutes.

Meanwhile, prepare the filling by half-boiling 4 medium potatoes until just tender. Once cool enough to handle, peel and dice them. In a heavy-bottomed pan or kadai, heat 2 tablespoons of oil and add 1 tablespoon of cumin seeds, letting them splutter. Then add 1 tablespoon each of coriander powder and garam masala along with red chili powder to taste. Sauté the spices for about 30 seconds before adding the diced potatoes. Cook for 15-20 minutes, stirring occasionally, until the potatoes are well coated with the aromatic spices, and finish with a sprinkle of chopped fresh coriander leaves.

Divide the rested dough into small balls and roll each into a thin circle. Cut each circle in half to form semicircles. Moisten the straight edge of a semicircle with a little water, then form a cone by bringing the two ends together. Fill the cone about three-quarters full with the spiced potato mixture and moisten the remaining edge to press it closed, forming a neat triangle.

Heat oil in a deep pan over medium heat and fry the samosas until they turn golden brown. Drain on paper towels.

Serve the samosas hot accompanied by mint-yogurt chutney, sweet tamarind chutney, or alongside spiced chickpea curry or a fresh salad.