Make the filling:
Heat the ghee or vegetable shortening in a large skillet over medium-high heat. Add the coriander seeds and cook until they darken slightly. Add the shallots and ginger, and cook until soft, about 2 minutes.
Add the diced cook potatoes to the skillet and sauté until slightly golden, about 3 minutes. Remove from the heat and add the peas, lemon juice, salt, garam masala, and cayenne, tossing gently to combine. Let the filling cool completely.
Prepare the spicy potato filling.
Make the dough:
In a wide, shallow bowl, mix the flour with the salt and baking soda. Make a well in the center and drop the shortening into the well. Pick up some flour and fat in one hand. Rub the other hand lightly over this mixture, moving from heel to fingertips, letting the fat-coated flour fall back into the bowl. Pick up more fat and flour and continue this rubbing action until the flour is evenly coated; it should have a fine texture with no lumps.
For crispy, flaky results, rub the fat into the flour.
Add the yogurt-water mixture a little at a time. Add just enough liquid until the dough comes together in a mass. Depending on the the flour and humidity, you may not need all the liquid; if you need more, add plain water a tablespoon at a time. Knead the dough until it's smooth and elastic. The dough is ready when it's no longer sticky and feels as soft as an earlobe, after about 5 minutes of kneading. Roll the dough into an 8-inch log, wrap it in plastic, and let it rest for about 15 minutes. (The dough can also be wrapped tightly and chilled for a day. Bring it to room temperature before continuing.)
Knead the dough until it's smooth and elastic.
Assemble the samosas:
Cut the dough into eight even pieces. Roll each piece into a ball and flatten slightly. Keep the pieces you're not working with covered with plastic wrap. Roll one flattened piece of dough into a thin 6-inch round, rolling from the center of the round and turning the dough frequently to achieve a uniform thickness. Cut the rolled circle in half.
Roll the dough into 6-inch round.
Pick up one semicircular piece of dough and moisten half of the straight edge with a little flour-water mixture. Create a cone by bringing the dry half of the straight edge over the moistened half. Press the seam together to close. Be sure to pinch closed the point of the cone as well; a good seam will keep the stuffing in during frying.
Cut the rolled circle in half--one half makes a samosa.
Fill the cone with two heaping tablespoons of the spicy potato mixture. Hold the cone about a third of the way up to keep it from collapsing as you fill. Brush one open side with the flour-water mixture and pinch the opening closed. To give the samosa its characteristic flared ruffle, continue to pinch the straight edge to slightly thin and extend it. Use remaining dough and filling to make 15 more samosas.
Fill the cone with two heaping tablespoons of the spicy potato mixture.
Fry the samosas:
Fill a heavy, deep pan with 4 inches of oil and heat it to 350° F (use a deep-frying thermometer to monitor the temperature). Add the samosas in batches of four or five, being careful not to crowd the pan. Cook the samosas, turning often, until they're golden brown, at least five minutes. Transfer samosas to a paper towel-lined plate to drain. Serve immediately or let them cool to room temperature.
Make Ahead Tips
Samosa dough can be wrapped tightly in plastic and refrigerated for a day, or frozen for up to three weeks. Assembled, uncooked samosas can be refrigerated, covered, for up to a day. Though samosas are best served immediately after cooking, they can be wrapped loosely in foil or plastic and stored in the refrigerator for up to two days. Reheat by dropping into 375° F oil for a minute and a half, or arrange samosas in a single layer on a baking sheet and place in a 350° F oven for 10 minutes.
nutrition information (per serving):
per samosa without dip;
Photo: Ben Fink