Whisk the cornstarch with ¼ cup water in a small bowl until smooth.
In a saucepan over medium heat, combine soy sauce, brown sugar, garlic powder, ground ginger, and honey. Stir in the cornstarch mixture and simmer until thickened, about 2 minutes. Remove from heat and let cool.
Place the salmon fillets in a large bag or bowl with the teriyaki sauce. Marinate for at least 30 minutes.
Preheat the oven to 400°F. Lightly coat a baking dish with cooking spray.
Transfer the marinated salmon fillets to the dish and bake for 18–20 minutes, until the fish flakes easily with a fork.
While the salmon bakes, whisk together the mayonnaise, sriracha, and condensed milk in a small bowl for the cream sauce.
Serve the salmon hot over rice and drizzle with the sriracha cream sauce.
