Combine all the tartar sauce ingredients in a small bowl, using salt to taste. Cover and refrigerate until ready to use.
Rinse the fish under cold water and pat dry with paper towels. Cut into 1-inch pieces and put in a bowl with the Worcestershire sauce, garlic, salt and pepper. Turn the fish to coat. Cover with plastic wrap and refrigerate for 20 minutes or up to 4 hours.
Place the flour in a shallow dish and toss the fish pieces in it, a few at a time, until evenly coated. Heat the oil in a large pot over medium-high heat. (To see if it's hot enough, place a small piece of bread in the oil; it should sizzle immediately.) Carefully add a few pieces of fish at a time, shaking off excess flour before placing them in the oil. Fry until golden brown, 4 to 6 minutes; transfer to a paper-towel-lined plate.
Meanwhile, heat a medium skillet over medium-high heat. Add a tortilla and warm for 10 to 20 seconds on each side. Place on a plate and cover with a kitchen towel; repeat with the remaining tortillas.
Spread a dollop of the chipotle tartar sauce on a warmed tortilla. Add a few pieces of cucumber and top with 3 or 4 pieces of fish, a few arugula and cilantro leaves and a little orange zest. Serve with lime wedges and more tartar sauce on the side.
Photograph by Tina Rupp
Recipe courtesy Ingrid Hoffmann for Food Network Magazine