Prepare the salmon: Cut the salmon fillet into 1-inch cubes, ensuring they’re relatively even in size for consistent cooking. Pat the pieces dry with paper towels to promote better searing.
Season the salmon: Place the salmon cubes in a bowl and lightly season with salt and pepper. Remember the soy sauce will add saltiness, so go easy on the salt.
Make the glaze: In a small bowl, whisk together the soy sauce, honey, minced garlic, and grated ginger until well combined. The honey might be thick, but keep whisking until it integrates smoothly.
Heat the pan: Place a non-stick skillet over medium-high heat and add the olive oil. Allow the pan to get hot but not smoking – you should see slight ripples in the oil.
Cook the salmon: Carefully place the salmon cubes in the hot pan, leaving space between pieces. Cook for about 2 minutes on the first side until golden brown.
Flip and continue cooking: Gently turn each piece to cook on another side for about 1-2 minutes. Salmon cooks quickly, so watch carefully to avoid overcooking.
Add the glaze: Pour the honey-soy mixture over the salmon and add red pepper flakes if using. Reduce heat to medium and cook for another 1-2 minutes, occasionally spooning the glaze over the salmon as it thickens.
Finish the dish: Once the glaze has thickened slightly and the salmon is cooked through (it should be slightly translucent in the center), remove from heat. Sprinkle with sesame seeds and green onions before serving.