In a bowl, combine soy sauce, honey or brown sugar, garlic, ginger, and sesame oil. Mix until smooth.
Submerge cod fillets in the marinade and refrigerate for at least 30 minutes.
Preheat the oven to 400°F (200°C).
Place marinated cod on a parchment-lined baking sheet and bake for 12-15 minutes until flaky and golden.
Garnish with chopped green onions before serving.
