1. To prepare crema, combine the first 6 ingredients; chill.
2. Preheat oven to 300°.
3. To prepare filling, heat a Dutch oven over medium-high heat. Add oil, and swirl to coat. Sprinkle pork evenly with 1/2 teaspoon salt. Add pork to pan; sauté 10 minutes, turning to brown on all sides. Remove pork from pan. Add onion and garlic to pan, and sauté for 3 minutes, stirring occasionally. Stir in cumin and chipotle chiles; sauté for 1 minute. Stir in 1 cup stock and the next 3 ingredients (through coffee); bring to a boil. Return pork to pan; cover. Bake at 300° for 3 hours or until pork is fork-tender. Remove pork from pan, and let stand 10 minutes. Shred pork. Return pork to sauce.
4. Increase the oven temperature to 450°.
5. To prepare masa, combine 2 1/2 cups stock and ancho chiles in a microwave-safe bowl. Microwave at HIGH for 2 minutes or until chiles are tender; cool slightly. Remove stems from chiles. Combine hot stock, chiles, and corn in a blender; process until smooth. Combine masa harina, 1 1/4 teaspoons salt, and baking powder, stirring well with a whisk. Cut in lard with a pastry blender or two knives until mixture resembles coarse meal. Add ancho mixture to masa mixture; stir until a soft dough forms. Turn dough out onto a lightly floured surface; knead dough until smooth and pliable. (If dough is crumbly, add water, 1 tablespoon at a time, until moist.)
6. To prepare tamales, immerse corn husks in water; weight with a plate. Soak 30 minutes; drain.
7. Working with one husk at a time (or overlap 2 small husks), place about 3 tablespoons masa mixture in the center of husk, about 1 inch from top of husk; press dough into a 4-inch-long by 3-inch-wide rectangle. Spoon about 1 heaping tablespoon pork mixture down one side of dough. Using the corn husk as your guide, fold husk over tamale, being sure to cover filling with dough. Use husk to seal masa around filling. Tear 3 or 4 corn husks lengthwise into strips; tie ends of tamale with strips. Place tamale, seam side down, on the rack of a broiler pan lined with a damp towel. Repeat procedure with remaining husks, masa mixture, and pork mixture. Cover tamales with a damp towel. Pour 2 cups hot water in the bottom of a broiler pan; top with rack.
8. Steam tamales at 450° for 25 minutes. Remove and rewet top towel, and add 1 cup water to pan. Turn tamales over; top with cloth. Bake for 20 minutes or until set. Let tamales stand 10 minutes. Serve tamales with crema.