Banana Leaf-Wrapped Lamb Shank Tamales with Morita Chile Salsa

Heat 1 tablespoon oil in a large Dutch oven over medium-high. Add tomatillos and tomatoes; cook, turning occasionally, until blackened in spots, 3 to 4 minutes. Add chiles and garlic; cook, turning often, until chiles are lightly toasted, about 1 minute. Transfer tomatillo mixture to a blender. Add chicken stock, and process until mostly smooth, about 20 seconds. Set aside.

Return Dutch oven to heat over medium-high, and add remaining 1 tablespoon oil. Season lamb shanks all over with 2 teaspoons salt and pepper. Cook lamb in hot oil, turning occasionally, until browned on all sides, 15 to 20 minutes. Add tomatillo mixture, and bring to a boil over medium-high. Reduce heat to low, partially cover with lid, and cook, turning lamb occasionally, until lamb is fork-tender and comes easily off the bone, about 3 hours to 3 hours and 30 minutes.

Transfer lamb shanks to a plate, and let stand until cool enough to handle, about 15 minutes. Meanwhile, cook braising liquid, uncovered, over medium-high, stirring often, until thickened to a salsa-like consistency and reduced to about 1 3/4 cups, about 30 minutes. Remove from heat. Finely shred lamb; discard bones. Add shredded lamb to reduced braising liquid, and toss to coat. Season to taste with salt and pepper. Let cool completely, about 1 hour.

Using tongs, warm banana leaf pieces, 1 at a time, over flame of a gas burner on medium-high, turning often, until leaves are glossy and pliable, about 10 seconds. Alternatively, microwave banana leaf pieces, 6 at a time, on a microwavable plate on high in 10-second intervals until leaves are glossy and pliable, about 30 seconds.

Place 1 banana leaf piece on a clean work surface with one short end closest to you. Using the back of a spoon, spread about 1/4 cup masa preparada lengthwise in center of leaf in a 5- x 4-inch rectangle of even thickness. Spoon about 2 tablespoons lamb mixture in a line down the center of masa rectangle, leaving a 1/2-inch border of masa above and below lamb mixture. Fold one side of banana leaf over so the masa encases the filling. Fold bottom and top ends of banana leaf toward center, and roll remaining leaf around the tamal, creating a tight package. Tie with a thin strip of banana leaf, if desired. Repeat with remaining banana leaves, masa preparada, and lamb mixture; reserve any remaining lamb mixture for another use.

Fill a large stockpot with 1 inch of water. Place a steamer insert (at least 7 inches deep) in stockpot, ensuring water does not touch bottom of steamer. Line bottom and sides of steamer with banana leaf pieces. Arrange tamales horizontally in steamer, overlapping slightly.

Heat pot over medium-high until steam is visible, 5 to 8 minutes. Place a layer of banana leaf pieces on top of tamales. Cover pot with a clean kitchen towel, and place lid on top. Reduce heat to medium-low, and cook 45 minutes. To test doneness, carefully uncover pot, and remove 1 tamal. Cover pot, and allow remaining tamales to keep cooking. Let tamal rest 10 minutes before unfolding. If masa sticks to banana leaf, rewrap tamal, and return to steamer basket. Continue cooking tamales 5 minutes before checking again for doneness. If banana leaf pulls away cleanly from masa, turn off the heat, and let tamales rest in pot, lid removed, banana leaves and kitchen towel in place, for 15 minutes.

While tamales rest, stir together onion, cilantro, lime juice, and remaining 3/4 teaspoon salt in a medium bowl. Serve tamales hot with onion relish.