How to Make It
In a medium saucepan, heat 2 tablespoons of the olive oil. Add the shallots and cook over moderate heat until softened, about 5 minutes. Add the water and simmer until reduced by half, about 6 minutes. Add the cream and simmer until reduced by one-third, about 6 minutes. Let cool for about 10 minutes.
Stir the parsley into the saucepan. Transfer the sauce to a blender and coarsely puree. Return the sauce to the saucepan. Stir in the lemon juice, season the sauce with salt and pepper and keep warm.
In each of 2 large nonstick skillets, heat 1 tablespoon of the remaining oil until shimmering. Season the halibut with salt and pepper and cook over high heat, turning once, until browned and just cooked, about 4 minutes. Transfer the halibut to plates. Serve with the parsley sauce.