Put potato and coconut milk into a sauce pan. Bring to a boil then simmer for 8 to 10 minutes (until the potatoes are softened but not mushy)
Add lime juice and mash
Season with salt and pepper and add 1 tsp oil (or a knob of butter)
Cook the scallops, 2 minutes on one side and 30 seconds on the other.
Remove from pan
Add garlic and whites of scallions and cook for 30 seconds
Add a quarter cup of water, roasted peppers, tomatoes, and chili sauce.
Cook until softened (4 to 6 minutes), smashing tomatoes into sauce
Add scallops, and juices back to pan and cook for 3 to 5 more minutes
Serve moqueca over the mashed potatoes