In a small bowl, whisk together honey, soy sauce, minced garlic, olive oil, grated ginger, black pepper, and red pepper flakes (if using) until well combined.
Place the salmon fillets in a shallow dish and pour the marinade over them. Cover and refrigerate for at least 30 minutes, or up to 2 hours for more flavor.
Preheat your grill or oven to 400°F (200°C).
Remove the salmon from the marinade and reserve the marinade for later use. If grilling, place the salmon skin-side down on the grill. If baking, place the salmon on a lined baking sheet.
Grill or bake the salmon for about 10-12 minutes, or until it flakes easily with a fork. Brush the reserved marinade over the salmon halfway through cooking for extra flavor.
Once cooked, remove the salmon from the heat and let it rest for a few minutes. Garnish with chopped green onions and sesame seeds before serving.