Step 1

In a medium bowl, combine the vinegar, sugar, 2 tablespoons salt, and garlic and stir until dissolved. Add the cucumbers and carrots and let sit, stirring occasionally, while you make the burgers.

Step 2

In another bowl, combine the fish, chopped cilantro, lemongrass, fish sauce, lime juice, ginger, and chili, and season with ½ teaspoon salt. Stir in ¼ cup of the panko and ¼ cup of the mayonnaise and form into 8 patties. Press the patties into the remaining panko. In a small bowl, combine the Sriracha and remaining mayonnaise. Heat the vegetable oil in a large nonstick skillet over medium heat until shimmering. Add the patties and cook, turning once, until golden brown and firm to the touch, about 5 minutes total.

Step 3

Spread the Sriracha mayonnaise on the cut sides of the bread and top with the fish patties. Use a slotted spoon to top with the cucumbers and carrots. Top with the whole cilantro leaves and drizzle some of the pickling liquid over top. Close the sandwiches and serve right away. Enjoy!