Place the shrimp in a large bowl and toss with the achiote paste and salt. Marinate the shrimp for 10 minutes.
Meanwhile, heat the canola oil to 350 degrees F in a tabletop deep-fryer or in a Dutch oven with a deep-fry thermometer attached. Place a wire rack over a sheet pan for draining. Fry the tortillas in small batches until crisped and golden, 4 to 6 minutes. Place on the rack to drain.
While the tortillas fry, heat 3 tablespoons canola oil in a large skillet over high heat. Add the shrimp and cook, turning once, until just cooked through, about 4 minutes. Set aside.
Spoon the Black Bean Puree over the bottom of a large oval platter. Arrange the fried tortillas over the top. Spoon the Queso generously all over. Top with the shrimp. Sprinkle with avocado, pico de gallo and pickled chiles. Garnish with cilantro.
Black Bean Puree:
Yield: about 4 cups.
Heat a 3-quart saucepan over medium heat. Add the oil, onions, jalapeno, coriander and cumin. Cook, stirring frequently, until the onion is soft, 4 to 6 minutes. Stir in the beans. Add the stock, crema and salt to taste. Bring to a simmer. Transfer the mixture to a blender and puree.
Yield: 6 cups.
Melt the butter in a 3-quart saucepan set over medium heat. Stir in the flour until combined. Cook, stirring, for 2 minutes. Switch to a whisk and slowly whisk in the milk and cream. Whisk in the salt. Switch back to a spoon and cook, stirring, until thickened, about 5 minutes. Stir in the Cheddar and Jack cheeses. Turn the heat off and allow the cheese to melt. Stir until smooth.
When blending hot liquid, first let it cool for five minutes or so, then transfer it to a blender, filling only halfway. Put the lid on, leaving one corner open. Cover the lid with a kitchen towel to catch splatters, and pulse until smooth.