Smashed potatoes are a great base for moist roasted halibut. The sauce is loaded with briny Kalamata olives, olive oil, and lemon juice and is perfect for the fish as well as the asparagus that is roasted alongside.
Pitted Kalamata olives, ⅓cup (2oz/60g) chopped
Extra-virgin olive oil, ¼cup (2fl oz/60ml) plus 2 tablespoons, plus more as needed
Fresh lemon juice, ¼cup (2fl oz/60ml) plus 1tablespoon
Preheat the oven to 450°F (230°C). In a small bowl combine the olives, ¼cup (2fl oz/60ml) of the olive oil, lemon juice, shallot, thyme, and lemon zest. Season to taste with salt and pepper.
Place the asparagus on a rimmed baking sheet. Drizzle with 2 tablespoons of the oil and toss to coat. Sprinkle lightly with salt and pepper and toss to coat. Spread in a single layer. Brush a small, rimmed baking sheet with oil, and place the fish on the baking sheet. Transfer 2 tablespoons of the sauce to another small bowl and brush over the fish; sprinkle on both sides with salt and pepper.
Roast the asparagus until just tender, 8–10 minutes, depending on their thickness. Roast the fish until almost firm to the touch, 5–8 minutes, depending on the thickness of the fillet.
Divide the asparagus among 4 warmed plates. Top with the fish, and spoon the sauce over. Arrange the potatoes alongside and serve right away.