This dish is a sampling of the cuisine you would find, at an open-air restaurant, in the heart of Mexico.
5 pasilla or mirasol chiles
2 medium tomatoes, halved lengthwise
2 tbsp. dried pumpkin seeds
1/2 tsp. ground cumin
6 whole cloves
1 small piece ginger (about 2'' x 1/2''),
peeled and finely chopped
6 cloves garlic, peeled
8 sprigs fresh cilantro
2 1/2 cups dried shrimp
2/3 cup fine dried bread crumbs
2/3 cup freshly grated parmigiano-reggiano
10 egg yolks, lightly beaten
10 egg whites
4 tbsp. vegetable oil
1 tbsp. masa harina
1 cup canned nopalitos
1. Place a small skillet over medium heat. Halve chiles, flatten on hot skillet, and toast, turning once, 10-15 seconds in all. Place chiles in a small bowl and add 1 cup hot water. Cover and set aside until soft and pliable, about 30 minutes. In same skillet, cook tomatoes over medium-high heat until soft but firm, about 2 minutes per side, then remove from skillet and set aside.
2. Drain chiles; remove stems and seeds. Combine chiles, tomatoes, pumpkin seeds, cumin, cloves, ginger, garlic, and cilantro in a blender and process until smooth. Combine mixture with 4 cups water in a saucepan. Bring to a simmer, uncovered, over medium-low heat. Simmer for 30 minutes, then strain sauce and set aside.
3. Process shrimp and bread crumbs in a blender until a fine paste is formed. Transfer to a medium bowl; stir in parmigiano-reggiano and egg yolks. In another bowl, whisk egg whites until stiff peaks form. Gently fold shrimp mixture into egg whites.
4. Scoop out 1/4 cup shrimp mixture and press gently between your palms to form a 2 1/2'' cake. Repeat with remaining shrimp mixture (yields 12 cakes).
5. Heat 2 tbsp. oil in a large nonstick skillet over medium-high heat. Fry shrimp cakes in batches until golden brown, about 2 minutes per side, adding more oil if necessary. Transfer cakes to a platter as they're done.
6. Pour 1/4 cup sauce into a bowl and whisk in masa harina until dissolved. Combine mixture and remaining sauce in shrimp skillet and simmer over medium-low heat. Add shrimp cakes and nopalitos. Cook for 25 minutes, periodically spooning sauce over cakes to moisten, and serve.