To prepare the tartar sauce: Combine the mayonnaise, garlic, scallion, chipotle, and lime juice in a small bowl and mix well. Add salt, to taste. Cover with plastic wrap and refrigerate until ready to use. Keep covered in the refrigerator up to 1 week.;
To prepare the tacos: Put the fish in a large bowl. Place the garlic cloves on a cutting board. Slice the cloves in half lengthwise and then smash with the side of a chef's knife. Sprinkle 1 teaspoon of salt over the garlic and chop and smear the garlic against the cutting board until it makes a paste. Add the garlic paste to the bowl of fish. Add the Worcestershire sauce and 1/2 teaspoon pepper; turning the fish to coat. Cover with plastic wrap and refrigerate for at least 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 they're all evenly coated. Shake off the excess flour.
Heat 2-inches of oil to 375 degrees F in a heavy skillet or deep pot over medium-high heat. Carefully add a few pieces of the fish at a time and fry until golden brown all over, about 4 to 6 minutes. Transfer to a paper towel-lined plate to drain. Season with salt and pepper while they are still hot. Allow the frying oil to return to temperature and continue to fry the fish in batches until finished.
Wrap the tortillas in a damp kitchen towel and place in the microwave. Microwave on full power for 30 seconds until they are soft and pliable. Keep warm.
To serve: Spread a dollop of the chipotle tartar sauce onto a warmed tortilla. Add a few strips of cucumber and top with 3 or 4 pieces of fish. Cover with a few arugula leaves, cilantro leaves, avocado, and a little orange zest. Serve with more tartar sauce on the side and lime wedges.
Recipe courtesy of Ingrid Hoffmann, 2008