Make the pastry: rub ghee into flour until crumbly. Add carom seeds and salt. Gradually add cold water and knead into a firm, stiff dough. Cover with a damp cloth and rest for 20 minutes.
Make the filling: heat oil, splutter cumin seeds, add peas, then mashed potatoes and all spices. Mix well and cook for 3-4 minutes. Stir in amchur and coriander. Let it cool completely.
Divide dough into 6 balls. Roll each into an oval about 15 cm long. Cut in half. Take one half, form a cone shape, fill with 2 tablespoons of filling, and seal the edges firmly with a little water.
Heat oil on moderate heat — not too hot. Test with a small piece of dough; it should rise slowly. Slide samosas in and fry on low-medium heat for 10-12 minutes, turning occasionally, until golden and crispy.
Drain on paper towels. Serve immediately with green chutney and tamarind chutney while the shell is still crispy.