Preheat oven to 350F. Combine 4 tablespoons butter and onion in large Dutch oven. Cover and bake until onion is golden brown, stirring occasionally, about 45 minutes. Stir spinach into onion and bake until just wilted, about 3 minutes. Remove from oven; keep warm. Season salmon with salt and pepper. Heat oil in heavy large skillet over high heat. Add salmon in batches and cook about 3 minutes per side for medium. Transfer to platter. Tent with foil to keep warm. Pour off excess oil from skillet. Add cream and vodka and boil until slightly thickened, about 4 minutes. Add green peppercorns and remaining 4 tablespoons butter and stir until butter is just melted. Mix in lime juice, season with salt and pepper. Divide spinach and onion mixture among plates. Top each with salmon fillet. Spoon sauce over. Sprinkle with snipped fresh chives. Posted to EAT-L Digest by Terry Pogue on Dec 25, 1997