Prep the salmon. Pat the salmon dry with paper towels. Cut into even 1-inch cubes.
Toss with a light sprinkle of salt, pepper, and the cornstarch until the cubes are just coated.
Stir the glaze. In a small bowl, whisk together honey, soy sauce, rice vinegar, sesame oil, garlic, ginger, and sriracha (if using). Set it near the stove.
Heat the pan. Place a large nonstick skillet over medium-high heat and add the oil. When it shimmers, it’s ready.
Sear the salmon. Add the salmon in a single layer without crowding.
Let it sear undisturbed for 1–2 minutes to develop color. Flip and cook another 1–2 minutes until mostly cooked but still a bit translucent in the center.
Glaze and reduce. Pour the glaze over the salmon. Toss gently to coat.
Lower heat to medium and simmer for 1–2 minutes, stirring, until the sauce thickens and turns glossy.
Finish. Remove from heat when the salmon is just cooked through and the glaze clings. Sprinkle sesame seeds and scallions if you like. Serve right away.