In a large Dutch oven or crock pot, simmer meat, onion and seasonings in about 5 cups of water for 3-4 hours, until tender. Set aside.
In a medium bowl, mix flour, salt and baking powder. Cut in the lard until well blended. Add liquid from the meat; mix into a dough. Divide dough in half. Roll out both halves; with one half, line a 12 x 16-inch (30 x 40-cm) pan. Fill with meat mixture. Cover with remaining dough. Bake at 375°F (190°C) for 30-35 minutes, until top is browned. Cool before cutting.