Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper or lightly grease it.
In a small bowl, whisk together the soy sauce, honey, rice vinegar, sesame oil, minced garlic, and grated ginger until well combined.
Place the barramundi fillets on the prepared baking sheet, skin side down. Season with salt and pepper.
Brush the soy sauce mixture generously over the top of the fish fillets.
Bake in the preheated oven for 12-15 minutes, or until the fish flakes easily with a fork and is cooked through.
Remove from the oven and let it rest for a couple of minutes.
Garnish with chopped green onions and sesame seeds before serving.