Dough 1) Place the flour in a medium-sized bowl. Mix in the salt. 2) Make a well in the center, and add the buttermilk or yogurt. Mix first with a spoon and then with your hand, to make a smooth dough. 3) Add extra flour, as needed, to keep the dough from being sticky. The dough will be quite soft. knead in the bowl for about 5 minutes. Cover tightly and refrigerate until you are ready to assemble the pastries.
Filling: 1) Peel the potatoes and chop them into 1-inch pieces. Place in a saucepan, cover with water, and boil until very soft. Drain and transfer to a medium-sized bowl. Mash and set aside. 2)Melt the butter in a heavy skillet. Add onion, garlic, ginger, mustard seeds, coriander, and salt. Saute over medium heat about 8 to 10 minutes, or until onions are quite soft. Add this to the mashed potatoes, along with the remaining ingredients. Mix well, but try not to smash the peas. Cool for at least 15 minutes before filling the pastries.
To Assemble and Bake: 1) Preheat the oven to 425 degrees F. Generously oil a baking sheet. 2) Keep a small container of flour, a fork, a small bowl of water, and a pastry brush close at hand. Flour a clean surface, and, one by one, roll 1-inch balls of dough into 5-inch circles, using a rolling pin. 3) Place approximately 1 1/2 tablespoons filling in the center of each circle, and fold over, just like a turnover. Brush the inside edges of each circle with a little water, and fold the edges together to make a small hem. Crimp the edges firmly with a fork. Store in the refrigerator or freezer until baking time. 4) To bake: Place the samosas on the oiled baking sheet. Brush the tops with oil. Bake 15 minutes at 425 degrees F., then reduce heat to 375 degrees F. and bake for 10 minutes more. For maximum crispness, turn the samosas over when you turn the oven down. 5) Serve within 5 minutes of baking, with Dipping Sauce. A nice way to serve the sauce is in individual saucers or tiny bowls, so each person can hold both samosa and sauce directly under his or her face while eating, and the sauce bowl can catch the drips. (It does drip, but that's one of the charms of this ritual.)
For the dipping sauce: 1) Place all ingredients in a small saucepan. Stir until the sugar dissolves. 2) Heat to boiling, then let simmer uncovered for about 10 minutes. it will reduce slightly. 3) Serve warm or at room temperature with hot samosas.
If you are storing the samosas to bake later on, place them on a heavily floured plate or tray, dust the tops with more flour, and cover tightly.
Recipe courtesy of Moosewood Cookbook: New Revised Edition by Mollie Katzen. Copyright 2000. Ten Speed Press, Berkeley CA