Allow the halibut to come to room temperature.
Mix the mayonnaise, 1 tbsp lemon juice, and sriracha in a small bowl and refrigerate.
Pat dry the fillets and then season with salt, pepper, and smoked paprika.
Heat a cast-iron skillet to medium. Sear fillets on both sides, flipping after a few minutes.
Turn off the heat, squeeze lemon juice over the fish, and set aside.
Prepare your preferred choice of bun.
Spread sriracha sauce on the halibut before adding it to the bun.
Serving suggestion: add microgreens, red onion, and avocado.
