Steps
1. Slice the onion thinly.
2. In a pan, melt 1 tbsp butter and add the sliced onion.
3. Cook the onion on low heat until caramelized, then stir in brown sugar.
4. Season the salmon fillet with salt and pepper.
5. In another pan, heat olive oil and 1 tbsp butter.
6. Sear the salmon fillet skin-side down first, then flip and cook until done.
7. Serve the salmon topped with caramelized onions.