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Choose fillets that look freshly cut. Avoid them if they have a strong, fishy odor. Try to cook your sole the same day for the freshest taste. If you can't cook the fillets right after buying them, store them in the coldest part of your fridge for up to 2 days.  Make sure frozen sole fillets also smell mild. Go for frozen fillets in tight packaging. Avoid any fish with visible ice or blood inside the package. Frozen sole fillets will last in the freezer for up to 3 months. Allow your oven to heat up completely while you prepare the sole for baking. Remove the crusts from the bread, then quarter each slice. Add the ingredients to the food processor and turn it on. Process the ingredients until the mixture looks smooth and uniform in texture. You need:  4 slices of fresh white bread 1 teaspoon (4 g) of lemon zest 1/4 cup (30 g) of walnut halves 1/4 cup (30 g) of grated Parmesan Drizzle the olive oil slowly into the mixture, continuing to process them with the food processor as you do so. Once the oil is fully incorporated, set the mixture aside. Rinse each fillet under cool tap water and pat the flesh dry. Season the fillets with salt and pepper to taste. Lay the 4 fillets out flat in a buttered 9 in (23 cm) x 12 in (30 cm) casserole dish. Set the buttered dish aside for now. Add 4 tablespoons of butter to a small saucepan and let it melt over medium heat. Meanwhile, juice the lemon. Add 1/4 cup (30 ml) of lemon juice and 3 tablespoons (42.4 g) of capers to the melted butter in the skillet. Stir the ingredients to combine them and remove the skillet from the heat. Drizzle the butter mixture evenly over the fish. Then sprinkle the breadcrumb mixture on top in an even layer. Place the uncovered casserole dish in the oven and bake the fillets for 15-20 minutes. You’ll know the fillets are cooked through when they are a uniform color throughout and the flesh flakes easily if you scrape the surface. While the sole fillets are baking, heat up 2 tablespoons (23.3 ml) of olive oil in a large skillet until it shimmers. Add 2 cloves of minced garlic and 2 bunches of chopped Swiss chard. Sauté until the chard is wilted. Add salt and pepper to taste and remove the skillet from the heat. The garlic-infused chard is served on the side, so you can omit this step if you don't like the taste of Swiss chard. Add 1 fillet to each serving plate. Divide the sautéed chard into 4 equal servings and add it on the side of each fillet. Serve the hot sole fillets immediately. Put any leftovers in an airtight container and refrigerate them for up to 4 days.

Summary:
Purchase sole fillets that look moist and smell mild. Preheat your oven to 400°F (204°C). Combine the bread, zest, nuts, and cheese in a food processor. Add 2 tablespoons (23.3 ml) of olive oil and process them until incorporated. Season both sides of the fillets and put them in a casserole dish. Melt the butter in a saucepan with the lemon juice and capers. Top the fillets with the butter sauce and the breadcrumb mixture. Sauté the garlic and chard over medium heat for 2 minutes. Serve the fillets immediately with the garlic-infused chard.