In a medium bowl, whisk together soy sauce, honey, Dijon mustard, olive oil, minced garlic, ground ginger, and black pepper until well combined.
Place the salmon fillets in a shallow dish or a resealable plastic bag. Pour the marinade over the salmon, ensuring each fillet is coated. Marinate in the refrigerator for at least 30 minutes, or up to 2 hours for more flavor.
Preheat the grill to medium-high heat. Lightly oil the grill grates to prevent sticking.
Remove the salmon from the marinade, reserving the marinade for basting. Place the salmon fillets skin-side down on the grill.
Grill the salmon for about 4-5 minutes per side, basting with the reserved marinade during the last few minutes of cooking. The salmon should be cooked through and easily flake with a fork.
Once cooked, remove the salmon from the grill and let it rest for a few minutes. Sprinkle with sesame seeds and garnish with sliced green onions before serving.