1. Adjust oven rack to middle position and heat oven to 325°F. Dissolve 2 1/2 tablespoons salt in 1 quart water. Transfer 1/2 cup brine to bowl, stir in sesame seeds, and let stand at room temperature for 5 minutes. Submerge fillets in remaining brine and let stand at room temperature for 15 minutes.

2. Drain seeds and place in 10-inch nonstick skillet. Cook seeds over medium heat, stirring constantly, until golden brown, 2 to 4 minutes. Transfer seeds to pie plate and wipe out skillet with paper towels. Remove fillets from brine and pat dry.

3. Place scallion white and orange zest on cutting board and chop until white and zest are finely minced and well combined. Transfer scallion-zest mixture to bowl and stir in orange juice, tahini, ginger, chili powder, and pinch salt.

4. Evenly distribute half of paste over bottoms (skinned sides) of fillets. Press coated sides of fillets in seeds and transfer, seed side down, to plate. Evenly distribute remaining paste over tops of fillets and coat with remaining seeds.

5. Heat oil in now-empty skillet over medium heat until shimmering. Place fillets in skillet, skinned side up, and reduce heat to medium-low. Cook until seeds begin to brown, 1 to 2 minutes. Remove skillet from heat and, using 2 spatulas, carefully flip fillets over. Transfer skillet to oven. Bake until center of fish is translucent when checked with tip of paring knife and registers 125°F, 10 to 15 minutes. Transfer to serving platter and let rest for 5 minutes. Sprinkle with scallion green and serve.

Serves 2