3. Heat a large saute pan over medium-high heat. Add the olive or grapeseed oil. Add the fish and sear until golden brown, about 2 minutes on each side. Transfer to the oven to keep warm.
4. Wipe out the pan and add the chorizo. Cook over medium heat until the sausage releases its oils, about 5 minutes. Remove the chorizo and set aside. Add 1 tablespoon olive oil, spinach, and the corn to the pan. Cook, stirring, until the spinach is wilted and the corn is cooked, about 5 minutes. Season with salt and pepper. Keep warm until serving.
5. In a medium saucepan over high heat, cook the wine and and reduce by half. Add the shallot and reduce heat to medium-high. Add the heavy cream and cook to reduce the liquid until thickened, about 10 minutes. Add the saffron and remove from heat. Gradually whisk in the butter, one tablespoon at a time, adding each tablespoon when the one before is incorporated. Season with salt and pepper.
6. To serve, divide the spinach among 4 plates. Top with the fish, then sauce. Sprinkle each plate with chorizo.