How to Make It
In a large frying pan, heat the oil or ghee over medium high heat. Add the onion and 1 teaspoon of sea salt and cook, stirring occasionally, until the onion is medium brown, about 8 to 10 minutes. Add the ginger and garlic and cook for 1 minute. Add all of the spices and cook for about 30 seconds, stirring constantly.
Stir in the crushed tomatoes and scrape the bottom of the pan to remove any browned bits. Add 1/2 cup of water to the pan, reduce the heat to low and simmer the sauce slowly for about 15 minutes, or until it thickens and begins to splatter. Add the prawns and cook for 2 minutes, just until they turn pink.
Remove from the heat and allow to cool for a couple of minutes, then stir in the heavy cream, if using. Season with sea salt to taste and garnish with chopped cilantro.
Basmati rice and naan, if desired.