serves 4
1 large (1/2-ounce) scallion
1/4 cup plus 1 tablespoon lower-sodium soy sauce
2 teaspoons grated fresh ginger (from a 1-inch piece)
2 1/2 tablespoons white miso
2 1/2 tablespoons mirin
4 (6-ounce) skin-on salmon fillets (1-inch thick)
Cooking spray
4 (4-ounce each) baby bok choy, halved lengthwise
2 teaspoons toasted sesame oil
1/2 teaspoon kosher salt
Cut scallion to separate white and light green bulbs from dark green tops. Finely chop bulbs, and place in a small bowl. Thinly slice dark green tops on an angle, and set aside.
Add soy sauce and ginger to chopped scallion bulbs in small bowl. Measure 2 tablespoons soy sauce mixture into a medium bowl and set aside. Add miso and mirin to remaining soy sauce mixture in small bowl; whisk until smooth. Arrange salmon fillets on a rimmed baking sheet; pour miso marinade evenly over salmon fillets to coat tops. Let marinate at room temperature until ready to use, about 10 minutes.
Preheat air fryer to 375°F for 10 minutes. Lightly coat fry basket with cooking spray. Remove salmon from baking sheet, letting excess marinade drip off. Add salmon in a single layer to air fryer; cook until a thermometer inserted into thickest portion of salmon registers 125°F, 7 to 8 minutes. Transfer salmon to a platter; tent with aluminum foil to keep warm.
While salmon cooks, toss together bok choy, sesame oil, and salt in a large bowl until coated. Set aside at room temperature until ready to use.
Arrange bok choy in an even layer in air fryer basket; cook at 375°F until bok choy is tender-crisp and leaves are crisp and charred, 5 to 6 minutes. Transfer bok choy to medium bowl with reserved soy sauce mixture; toss until bok choy is fully coated. Arrange marinated bok choy on platter with salmon; drizzle bok choy with remaining soy sauce mixture. Sprinkle reserved sliced dark green scallions on top and serve.