Preheat your oven to 400°F. Line a baking sheet with parchment paper or lightly grease it.
In a small bowl, whisk together the soy sauce, honey, rice vinegar, sesame oil, garlic, and ginger until well combined.
Place the salmon fillets on the prepared baking sheet, skin side down. Pour half of the glaze over the salmon, reserving the other half for later.
Bake the salmon in the preheated oven for 12-15 minutes, or until it flakes easily with a fork.
While the salmon is baking, combine the cornstarch and water in a small saucepan over medium heat. Stir until the mixture thickens, then add the reserved glaze. Cook for an additional 2-3 minutes until heated through.
Once the salmon is done, remove it from the oven and brush the thickened glaze over the top. Sprinkle with sesame seeds and sliced green onions before serving.