Heat the coconut oil in a large skillet over medium heat and add the garlic. Saute for 1-2 minutes, or until it just starts to brown.
Add the sliced red peppers and the white parts of the green onions and cook for 2 minutes, until the vegetables start to soften.
Add the curry paste and fry, while stirring constantly, for about 30 seconds.
Add the fish sauce, coconut sugar and coconut milk and bring to a simmer for 5 minutes.
Add the shrimp, turn off the heat and cover. Let it sit for 10 minutes, until the shrimp has turned pink and is cooked through.
Once the shrimp is cooked, stir in the basil leaves and add any additional salt to taste. Squeeze a touch of fresh lime juice over the top for an extra fresh burst of flavor.
If the curry is too thin, add 1 tablespoon of cornstarch to 1 tablespoon of water in a small bowl and mix well to make a cornstarch slurry. Add the slurry, just a little at a time while stirring until the desired consistency has been reached.
You can also fry your shrimp in a separate pan while your curry cooks and stir it in in the end. Fry just until the shrimp turns pink. This will save you about 10 minutes if you're in a hurry (though I prefer poaching them for the best results).
Full fat coconut milk or coconut cream is a must to ensure the curry doesn't come out watery.