Poached Sea Bass with Spinach and Asparagus

For one portion:1 (9 oz.) Sea Bass fillet, 1 tbsp. butter, 1 cup fresh spinach, 10-15 asparagus spears, 1/4 sliced onion, coconut cream, salt and pepper. Season the Sea Bass and place it in roasting pan, pour 3 tbsp. water, cover with aluminum foil and put in a preheated oven to 425 F. for about 12 minutes. Sea Bass is expensive and delicate fish and I find