Pat the fish strips dry using paper towels and season them lightly with salt and pepper.
In a large bowl, whisk together the flour, baking powder, smoked paprika, garlic powder, salt, and pepper. Gradually add the cold sparkling water while whisking until a smooth, slightly thick batter forms.
Heat vegetable oil in a skillet to about 2 inches deep, warming it to 350°F (175°C).
Dip each fish strip into the batter, allowing any excess to drip off, then carefully place them into the hot oil without overcrowding. Fry for 3 to 4 minutes per side, or until golden and crispy. Transfer to paper towels to drain.
While the fish is frying, combine the mayonnaise, toasted sesame oil, grated ginger, soy sauce, rice vinegar, honey, lime juice, and Sriracha in a medium bowl. Whisk until the sauce is smooth.
Warm the tortillas in a dry skillet or in the oven.
To assemble the tacos, spread the sauce on the tortillas, then top with the crispy fish, shredded cabbage, fresh cilantro, and pickled jalapeños if desired. Serve with lime wedges on the side.