HALIBUT AND SALMON TERRINE WITH AIOLI AND HORSERADISH

Halibut and Salmon Terrine with Aioli and Horseradish image

Provided by Martha Stewart

Time 3h

Number Of Ingredients 20

2 tablespoons extra-virgin olive oil
1 large sweet onion, chopped
12 ounces boneless, skinless halibut fillets, cut into chunks
12 ounces boneless, skinless wild salmon fillets, cut into chunks
2 large eggs
3/4 cup cold water, plus boiling water for pan
3 tablespoons matzo meal
1 tablespoon sugar
1/2 teaspoon fresh lemon juice
Coarse salt and freshly ground pepper
1/2 large carrot, peeled and grated
1/2 large parsnip, peeled and grated
1 tablespoon chopped fresh dill
1 garlic clove
Coarse salt
1 large egg yolk, room temperature
Juice of 1/2 lemon
1/2 cup light olive oil or peanut oil
1/2 cup extra-virgin olive oil
Store-bought horseradish with beets, for serving

Steps:

Preheat oven to 325 degrees. Make the terrine: Coat a 5-by-9-inch loaf pan with 1 1/2 teaspoons olive oil. Heat remaining olive oil in a skillet over medium heat. Cook onion, stirring, until soft, 6 to 8 minutes.
Pulse halibut and salmon in a food processor until finely chopped (not smooth).
Beat eggs with a mixer on medium speed until frothy, about 2 minutes. Beat in onion, fish mixture, cold water, matzo meal, sugar, lemon juice, 2 teaspoons salt, and some pepper until well combined, about 3 minutes. Beat in carrot, parsnip, and dill.
Transfer mixture to pan. Smooth top using an offset spatula. Cover with parchment-lined foil, and transfer to a large roasting pan. Pour enough boiling water into roasting pan to come halfway up the sides of the loaf pan. Bake until terrine is firm in the center, about 45 minutes. Remove pan from water. Let cool for 10 minutes.
Meanwhile, make the aioli: Mash garlic and a pinch of salt using a mortar and pestle or the side of a knife until a paste forms. Transfer to a bowl. Whisk in egg yolk and lemon juice. Gradually whisk in oils.
Run a knife or an offset spatula around the edge of the pan to loosen terrine. Place a plate on top, then flip. Tap top and sides gently several times to help release terrine. Let cool completely. Soak up any released juices with a paper towel. Refrigerate, covered with plastic wrap, for at least 1 hour.
Uncover terrine. Slice, and serve with dollops of aioli and horseradish.