Adjust oven rack to the top position and preheat oven to 450 degrees. Wash and dry all produce. Cut potatoes into 1/2-inch wedges. Toss on a baking sheet with a large drizzle of oil and half the Fry Seasoning (you’ll use the rest in step 4), salt, and pepper. Roast until golden brown, 20-25 minutes.

While potatoes roast, halve, core, and thinly slice apple. Halve lemon. In a large bowl, toss apple slices with the juice from 1 lemon half.

In a small bowl, combine sour cream and mayo. Stir in 1/2 tsp horseradish powder and a small squeeze of lemon juice. Add more horseradish and/or lemon juice to taste. Season with salt and pepper.

Pat barramundi dry with paper towels. Season all over with salt and pepper. Season flesh side with remaining Fry Seasoning. Heat a large drizzle of oil in a large pan over medium-high heat. Add fish to pan skin sides down. Cook until skin is crispy, 4-5 minutes. Flip and cook until fish is opaque and cooked through, 2-3 minutes more.

Add lettuce to bowl with apple slices. Season with salt and pepper. Toss with a drizzle of olive oil.

Divide potatoes, salad, and barramundi between plates. Drizzle a small amount of horseradish sauce over fish and serve the rest on the side for dipping.