Mix flour and salt in a large mixing bowl. Cut margarine into small pieces and rub into flour with a pastry cutter until crumbly. Add water. Mix well with hands until a smooth dough forms, cover with a damp cloth.
Heat the ghee or oil in a skillet and add the asafetida powder, mustard seeds, potatoes, peas, chiles, salt and pomegranate seeds, if using. Stir well over moderate heat for 2 minutes. Add peas, potatoes and cauliflower. Cover the pan, reduce heat, and cook gently for 10 minutes.
Remove the pan from heat and add the garam masala and chopped cilantro. Stir well and then leave the filling to cool before using to stuff the samosas.
Divide the samosa dough into 12 equal portions and roll out each one to a thin circle, about 7 inches in diameter. Cut each circle in half with a sharp knife and then cover the semicircles with a damp cloth while you fill them one at a time.
Brush the edges of the semicircle with a little milk and spoon some of the filling on to the center. Fold in the corners, overlapping then to form a cone. Fold over and seal the top to make a triangle. Deep fry in hot oil in batches, until crisp and golden. Drain on paper towels and serve hot with chutney!