How to Make It
Finely grate 1/2 teaspoon of zest from the lemon; wrap the grated zest in plastic. Using a vegetable peeler, remove the remaining zest from the lemon in wide strips. Cut the strips into thin julienne. Squeeze 1 tablespoon of juice from the lemon.
In a medium skillet, combine the olive oil with the pepper berries and the lemon julienne and bring to a boil. Simmer the oil over low heat for 20 minutes. Pour the oil through a fine strainer set over a bowl, pressing on the solids.
Return the oil to the skillet and bring to a simmer. Add the salmon fillets, season with salt and pepper and simmer over moderately low heat until cooked on the bottom, about 5 minutes. Using a metal spatula, carefully turn the fillets over and cook until just opaque throughout, about 5 minutes longer. Transfer the salmon to a warmed platter or plates.
Ladle out all but 1/4 cup of the olive oil and set the skillet over moderately high heat. Add the lemon juice and orange juice and boil for 1 minute. Remove the skillet from the heat. Add the grated lemon zest and gradually whisk in the butter. Season the sauce with salt, pour it over the salmon fillets and serve.