FOR THE CHERMOULA: Process all of the ingredients together in a food processor until smooth, about 20 seconds, stopping to scrape down the sides of the bowl as needed. Transfer to a serving bowl and set aside. (The chermoula can be refrigerated in an airtight container for up to 2 days.).
FOR THE HALIBUT: Adjust an oven rack to the middle position and heat the oven to 425 degrees. Pat the halibut dry with paper towels and season with salt and pepper. Heat the oil in a 12-inch ovenproof skillet over high heat until just smoking. Turn the heat to medium-high, carefully lay the steaks in the pan, and sear until spotty brown, about 4 minutes. Off the heat, flip the steaks over using two thin-bladed metal spatulas.
Transfer the skillet to the oven and roast the halibut until the flesh is opaque and the fish flakes apart when gently prodded with a paring knife, about 9 minutes. Transfer the steaks to a carving board, separate the skin and bones from the fish with a spatula. Spoon 1 tablespoon of the chermoula over each piece of fish and serve immediately, passing the remaining chermoula at the table.