Crispy Fried Fish Sandwich

To make the tartar sauce, add lemon zest, lemon juice, white vinegar, and grated shallot to a wide-mouth jar. Let it sit for a few minutes to mellow the shallot.

Add a pinch of kosher salt, Dijon mustard, and one room-temperature pasteurized egg to the jar.

Carefully pour the avocado oil over the egg, trying not to break the yolk.

Place an immersion blender over the yolk at the bottom of the jar. Blend without moving until it begins to emulsify, then slowly move the blender up and down to incorporate all the oil and create a thick mayonnaise.

To the mayonnaise base, add the chopped sweet gherkins, rinsed and chopped capers, chopped fresh dill, and chopped fresh chives.

Add another pinch of kosher salt, stir everything together, and set the tartar sauce aside.

Cut the fish fillets into portions that will fit on your buns. Place them on a wire rack set over a baking sheet.

Season the fish generously on all sides with kosher salt and let it rest for 20 minutes to draw out excess moisture.

While the fish rests, pour several inches of neutral oil into a Dutch oven or heavy-bottomed pot and heat to 375°F.

To make the batter, whisk together the all-purpose flour, cornstarch, baking powder, garlic powder, onion powder, paprika, and a generous amount of kosher salt in a large bowl.

Slowly whisk in the cold sparkling water until the batter is smooth. Let it rest for a few minutes to fully hydrate.

Pat the fish fillets completely dry with a paper towel.

Dip each piece of fish into the batter, ensuring it's fully coated, and let any excess drip off.

Carefully lower the battered fish into the hot oil. Fry in batches for 3-4 minutes, until golden brown and crispy. Do not overcrowd the pot.

Remove the fried fish to a clean wire rack to drain and immediately season with more kosher salt.

To assemble, place lettuce on a toasted brioche bun, followed by a piece of fried fish, and a generous spoonful of the homemade tartar sauce. Top with the other half of the bun and serve immediately.