Preheat the oven to 400 degrees F. Place the halibut in a parchment paper-lined baking dish. Drizzle fish with the oil; season with salt and pepper. Bake the fish 15 minutes, or until cooked through.
Meanwhile, place the remaining ingredients, except chopped cilantro and garnish, in a medium pot. Bring to a simmer over medium, medium-high heat. Simmer until the coconut milk had reduced by about a 1/3 and the sauce has lightly thickened. Mix in the chopped cilantro and reserve sauce on low heat.
When the fish is cooked, ladle a generous amount of the sauce in each of 4 shallow serving bowls. Set a piece of fish in each bowl, garnish with lime slices and cilantro sprigs, and serve.
Recipe Options: Instead of halibut, try another fish fillet in this recipe, such as salmon or cod. Instead of cilantro, try another fresh herb in the sauce, such as mint or basil. Instead of fish, try serving the sauce with grilled or pan-seared seared chicken breasts, lamb chops, or pork chops.