1-First Step: Heat the oven and set up the pan. Start by heating your oven to 425°F or 217°C. Line a rimmed baking sheet with parchment paper, then place a rack on top and spray it with cooking spray. This setup matters because it lifts the fish off the pan, which helps the bottom stay crisp instead of soggy. While the oven heats, pat the fish dry with paper towels. Dry fish holds the coating much better than wet fish, so do not skip this part. Season both sides lightly with salt and pepper.

2-Second Step: Toast the panko mixture. Set a skillet over medium heat and add 1 tablespoon butter. Once it melts, stir in the 1 cup Panko breadcrumbs, zest of 1 lemon, and 1 tablespoon Cajun seasoning. Toast the mixture for about 5 minutes, stirring often, until it turns golden brown and smells nutty. This quick stovetop step is what gives the fish its crunchy finish. If the crumbs look like they are browning too fast, lower the heat a little. You want golden crumbs, not dark ones.

3-Third Step: Mix the coating binder. In a shallow dish, stir together 3 tablespoons mayonnaise, 1 tablespoon Dijon mustard, 1 teaspoon lemon juice, and 1 teaspoon thyme. Mix until smooth. This coating adds flavor and gives the breadcrumbs something to stick to. Spread the mayo mixture in a thin layer on both sides of each fish piece. You do not need a heavy coat. A light layer is enough to help the crumbs cling without making the fish taste greasy.

4-Fourth Step: Coat the fish. Press each mayo-coated fish piece into the toasted panko mixture. Turn gently and pat the crumbs on so they stick well. Make sure each piece has an even crust on all sides if you want full coverage. Place the breaded fish on the prepared rack in a single layer. Leave a little space between pieces so the hot air can move around them. If the fish is crowded, the coating can steam instead of crisp.

5-Fifth Step: Bake until flaky. Put the baking sheet on the middle rack of the oven. Bake for 7 to 10 minutes, depending on thickness. Thin fillets may cook closer to 7 minutes, while thicker pieces may need the full 10 minutes. The fish is done when it flakes easily with a fork and reaches an internal temperature of 135°F or 57°C. If you do not have a thermometer, gently check the thickest part of the fish. It should look opaque and separate in flakes.

6-Final Step: Serve with lemon and a dipping sauce. Move the fish to plates and serve right away with lemon wedges. Add tartar sauce, seafood cocktail sauce, plum sauce, honey mustard, or lemon garlic mayo if you want extra flavor. For a full meal, pair it with roasted vegetables, rice, or a simple salad.