Pre-heat oven to 190 °C bake. Prepare the fish by rinsing under cold water. Pat dry with a paper towel.
Place fish in a dish lined with baking paper. Rub salt all over whole fish.
Stuff the fish cavity with lemon slices, half of the garlic, ginger and butter. Cover fish with baking paper and bake for 30-35 minutes. Check after 25 minutes to avoid overcooking.
Meanwhile, in a saucepan heat soy sauce, vinegar, sesame oil, Red Pepper & Chilli Jelly, and the remaining ginger and garlic. Bring to a boil and season with salt and pepper to taste. Remove from heat and cool.
Remove fish from oven and rest for 5 minutes. Pour sauce over the fish and garnish.
If Blue Cod is unavailable, Snapper can be used. To avoid overcooking, always cook fish medium rare, as it continues to cook after you remove it from oven. Squeeze a little fresh lemon juice to bring freshness and acidity to the dish