Pat the salmon dry with paper towels. Season both sides with salt and black pepper. Dry surfaces sear better and help the glaze stick.
Whisk the glaze: In a small bowl, combine orange juice, zest, soy sauce, honey, rice vinegar, garlic, ginger, and red pepper flakes.
Preheat the pan over medium to medium-high heat.
Add the oil and swirl to coat. You want the pan hot before the fish goes in.
Sear the salmon skin-side down for 3–4 minutes without moving it. Press gently with a spatula to keep the skin flat and crisp.
Flip and cook 2 minutes on the second side.
You’re building color, not fully cooking yet.
Pour in the glaze around the salmon. Lower the heat to medium. Spoon the bubbling glaze over the fillets as it reduces, 2–4 minutes.
Thicken if needed: If you prefer a sticky finish, stir the cornstarch and water together, then add to the pan.
Simmer 30–60 seconds until glossy.
Finish to desired doneness: Aim for an internal temp of 125–130°F (52–54°C) for medium, or cook to your preference. The salmon should flake but still look moist.
Rest 2 minutes. Plate the salmon and spoon extra glaze on top.
Garnish with green onions, sesame seeds, and orange wedges if you like.
Serve with rice, quinoa, or a crisp salad. Roasted broccoli or green beans make an easy side.