This salmon is delicious hot, cold or room temperature. The horseradish flavor mellows when cooked and the dish is great served at brunch with pickled cucumber and onion on the side, or at dinner with wild rice flavored with dried fruit and nuts and a caesar salad.
As simple as it is, this is a wonderful, elegant holiday dish - easily made ahead and beautiful when presented whole on a bed of baby spinach.
To most easily remove the fish to a serving platter in one piece, bake it on a non-stick surface. For a larger, 4 lb filet, make 1.5 times the recipe for topping.
Place horseradish in a clean dish towel and wring it until liquid no longer comes out. When unwrapped, the horseradish should hold together in a dry, almost solid ball.
Reconstitute the horseradish by mixing it with 1/2 cup mayonnaise, forming a smooth paste. Combine with remaining topping ingredients.
Place salmon, flat side down, on a Silpat or non-stick foil-lined baking sheet.
Cover the entire surface of the fish with the topping, making the topping layer thickest over the thickest part of the fish.
The surface of the topping may be decorated - in picture 2 the back of a teaspoon was used to make rows of small indentations resembling (?) fish scales.
Bake at 425 degrees for 30 minutes, or until the topping has been partially absorbed into the fish and turned deep, golden brown. With all of the mayo in the topping, the fish really doesn't dry out.
When done, carefully remove the layer of oil that has collected on the baking sheet by blotting it with paper towels. Pouring the oil off is pretty risky if the fish is on Silpat or non-stick foil! When the baking sheet is clean, slide the fish onto the serving platter by tilting the baking sheet.
Or, leave the oil alone and move the fish using two large spatulas.