In a mixing bowl, combine honey, soy sauce, minced garlic, grated ginger, rice vinegar, sesame oil, and red pepper flakes (if using). Whisk together until well mixed.
Season the salmon fillets with salt and pepper on both sides.
Place the salmon fillets in a shallow dish and pour the honey garlic mixture over them, ensuring they are well coated. Cover and marinate in the fridge for 15-30 minutes.
Preheat the oven to 375°F (190°C).
Line a baking sheet with parchment paper or lightly grease it with cooking spray.
Remove the salmon from the marinade, reserving the marinade for later use. Place the salmon fillets on the prepared baking sheet.
Bake in the preheated oven for 12-15 minutes, or until the salmon flakes easily with a fork and is cooked through.
While the salmon is baking, pour the reserved marinade into a small saucepan and bring it to a simmer over medium heat. Cook for about 5 minutes, allowing it to thicken slightly.
Once the salmon is done baking, drizzle the thickened glaze over the fillets.
Remove from the oven, garnish with sliced green onions and sesame seeds, and serve immediately.
Notes
For a gluten-free option, use tamari instead of soy sauce.