Whip the cream cheese in a stand mixer fitted with the whisk attachment or in a bowl with a handheld mixer until soft, and then add the heavy cream. Continue to whip until light and fluffy.
Fold in the garlic, pimientos, green onion, and lemon juice. Season to taste with salt and pepper.
Place a large skillet over medium-high heat. Add enough oil to coat the skillet, about 2 tablespoons.
Season the fish with salt and pepper, then lightly dust it with cornstarch. Shake the excess off the fish.
When the oil is hot but not smoking, add the fish (flesh side down if it has skin on it) to the skillet. If the skillet is too hot, lower the heat.
Let the fish brown on the bottom, allowing it to cook at least two-thirds of the way through, 5 to 6 minutes depending on the thickness of the fish. You’ll see it become slightly opaque on the sides. Remember the rule of thumb: Fish cook through in about 10 minutes for every inch of thickness.
With a fish spatula, gently lift the fish off the pan and flip to the other side. Let cook until golden on the bottom and the fish begins to flake or separate a bit on the top. Transfer to plates or platter and serve with a dollop of the pimiento sauce.