Methods

1. To make the dough, combine the all-purpose flour, fine sea salt, and ajwain seeds in a large bowl and mix well. Add the melted ghee and, using your fingertips, rub it into the flour (as you would for making a shortcrust pastry) until the mixture looks like coarse sand. 
2. Add ½ cup water and gently bring the dough together. If the dough is too dry, add 1 tablespoon at a time until it comes together. Turn out onto a clean surface and knead it a few times until it forms a ball, about 30 seconds. (This is a pastry, so make sure not to over-knead!) Flatten the dough into a rectangle, wrap in plastic wrap and let sit at room temperature for 45 minutes.
3. Meanwhile, make the filling. Place 1¼ pounds Yukon gold potatoes in a medium pot, cover with cold water and add 2 tablespoons fine sea salt (this is your chance to season the potatoes from the inside out!). Place the pot over medium-high heat and bring to a boil. Reduce the heat to medium and simmer until the potatoes are tender, about 20 to 30 minutes, depending on the size of your potatoes. Drain and let cool for 10 minutes. Remove the peels, discarding them or saving them for another use, and set the peeled, cooked potatoes aside.
4. Heat the ghee in a large skillet over medium heat. Add the cumin seeds and cook until they start to turn light golden and become fragrant, 15 to 45 seconds. Add the serrano pepper and continue to cook until it starts to soften, 1 to 2 minutes more. Add the garam masala, turmeric, and Guntur Sannam chilli powder, and continue to cook, stirring frequently, to bloom the spices, 30 seconds. 
5. Reduce the heat to medium-low, add the cooked potatoes, then using the back of a spoon, break them up into small pieces, ranging in size from a pea to a marble. Stir in the peas, amchur powder, black salt, if using, cilantro, and the remaining 1 teaspoon fine sea salt. Turn off the heat and set aside.
6. To assemble the samosas, unwrap the dough and divide it into eight, equal pieces. Loosely rewrap the pieces you aren't using in the plastic wrap., Working with one piece at a time, roll into a ball, gently flatten with your palm, and then using a rolling pin, roll it into an oval about 8x6 inches. Cut the oval in half crosswise, so you are left with two half moons, 4x6 inches.
7. Take one half moon and lightly wet the straight edge with water using your fingers. Bring the two straight edges together, slightly overlapping by ¼-inch and pinching together to create a cone. Nestle the cone in your hand with the seam resting on your index finger and the other side draped over your thumb. Spoon 2 tablespoons of filling into the cavity, gently packing it in with the back of the spoon. To close, lightly wet one side of the edge of the cone and then press the two edges together to seal the samosa. Place on a baking sheet, cover with a clean kitchen towel and repeat with the remaining dough and filling.
8. To fry the samosas, heat about 3 inches canola oil in a large pot or Dutch oven over medium high heat to 300°F. Fry the samosas in batches. Gently place half of the samosas in oil and fry until the wrappers start to turn very light golden, 4 to 5 minutes. Increase the heat to high and continue to fry the samosas until they are golden brown, 3 to 4 minutes more. Transfer the fried samosas to a wire rack-lined sheet pan. Repeat the frying process with the remaining half.
9. Serve warm or at room temperature with the chutney of your choice.