Special equipment: 3-inch round cookie cutter, 6 small (1/2-inch-wide) cannoli forms
Heat the olive oil in a large nonstick skillet over medium-high heat until it is very hot but not smoking. Add the fish and cook, carefully turning once to avoid breaking the fillets, until lightly browned on both sides, about 3 minutes.
Mix the sambal oelek, ground ancho and salt together. Spread generously over the fish and continue cooking until the fish is barely opaque when flaked with the tip of a small knife, about 2 minutes more. Remove from the heat and add the lime juice and cilantro. Let the fish cool completely in the liquid. (The fish and its liquid can be transferred to a shallow dish, covered and refrigerated for 1 day.)
Use a 3-inch round cookie cutter to cut out 18 rounds from the tortillas. Pour enough vegetable oil to come about 3/4 inch up the side of a heavy deep skillet and heat over medium-high heat until the oil is shimmering. Line a baking sheet with paper towels and place near the skillet. Have ready 6 small (1/2-inch-wide) cannoli forms. (If you have more forms, use them, but if you have only 6, they can be reused after they cool.)
Working with one tortilla round at a time, use tongs to dip a round in the oil just until it softens, about 3 seconds. Transfer to the paper towels. Place a cannoli form across the center of the round. Let the round cool slightly, then fold up the sides to make a taco-shell shape. Holding the round and cannoli form together with the tongs, transfer them to the hot oil and fry until the shell holds its shape, about 15 seconds. Let go of the shell and continue deep-frying until the shell is golden brown, about 30 seconds more. Return to the paper towels. (With practice, this will take less than a minute per shell and you can do more than one at the same time.) Let cool slightly; slide the form out of the shell. (The shells can be covered loosely with plastic wrap and stored at room temperature for up to 6 hours.)
Drain the fish and discard the marinade. Heat a large nonstick skillet over medium heat. Add the fish and cook, turning once, until warmed through, about 2 minutes. Do not overcook. Remove from the heat. Smear about 1/2 cup guacamole over the fish and set aside to warm the guacamole, about 2 minutes. Transfer to a bowl and use 2 forks to break the fish mixture into bite-sized pieces.
Divide the fish filling among the taco shells. To each taco, add about 1 tablespoon mango salsa and a drizzle of the chipotle cream. Transfer to a platter, add the lime wedges and sprinkle with cilantro. Serve immediately, with any remaining guacamole, salsa and chipotle cream on the side.
Photograph by Ryan Liebe
You'll have tortilla scraps after cutting out the mini taco shells. Fry them, salt lightly and serve as chips with leftover guacamole and salsa.