1. Make the fry bread: Combine the flour, dry milk solids, baking powder, and salt, and sift them into a deep bowl.
2. Add the lard bits and, with your fingertips, rub the flour and fat together until the mixture resembles flakes of coarse meal.
3. Pour in the water and toss the ingredients together until the dough can be gathered into a ball. Drape the bowl with a kitchen towel and then let the dough sit at room temperature for about 2 hours.
4. After sitting, tear the dough into 6 equal pieces. Then, on a lightly floured surface, roll each dough ball into a circle about 4 inches in diameter and 1/4-inch thick. With a small knife, cut 2 (4- to 5-inch) long parallel slits completely through the dough, down the center of each rolled piece, spacing the slits about 1-inch apart.
5. In a heavy, 10-inch cast iron skillet, melt the remaining pound of lard over moderate heat until it is very hot but not smoking. The melted fat should be about 1-inch deep; add more lard if necessary.
6. Fry the rolled dough, 1 at a time, for about 2 minutes on each side, turning them once with tongs. The bread will puff slightly and become crisp and brown.
7. Drain the Navajo fry bread on paper towels and serve warm.
8. To make the tacos: Brown the ground beef in a saute pan. At the end, add refried beans to heat.
9. Divide equally onto 6 fry bread rounds. Top with cheese, lettuce, tomatoes, green chiles, onions, and salsa, if desired.

Makes 6 4-inch round tacos.