Line baking tray with a small piece of parchment paper.
Combine Marmite, hot water, and sweet chili sauce in a small bowl.
Remove salmon skin. Rinse and pat dry with paper towel. Sprinkle salt and pepper onto salmon.
Drizzle sauce over salmon. Let it sit for 10 minutes.
Place in the oven and broil or grill for about 6 minutes.
Remove from oven. Using a spoon, scoop up sauce from the side of the baking tray onto the salmon.
Drizzle vegetable oil over the salmon.
Return the baking tray to the oven and continue to broil or grill for another 6 minutes.
Remove and serve immediately.