Thinly slice the carrots. Season the fish with salt. Melt 15g butter in a medium deep frypan over medium heat. Cook the fish for 3½-4 mins each side or until browned and just cooked through. Remove from the pan.
Step 2 — Start sauce
Return the pan to medium heat, add the carrot and cook, stirring, for 2 mins or until slightly softened. Add 1 tsp plain flour and 3 tsp pepper and garlic seasoning (see Make it milder) and cook, stirring, for 1 min or until golden. Gradually stir in 60ml (¼ cup) milk and 60ml (¼ cup) water until smooth and combined.
Step 3 — Finish sauce
Increase the heat to high and bring the sauce to the boil, stirring constantly. Simmer for 1 min or until slightly thickened. Add the fish and stir until combined and the fish breaks down into smaller pieces. Remove the pan from the heat. Stir in the horseradish dressing. Taste, then season with salt.
Step 4 — Grill fish bake
Preheat the grill to high. Put the breadcrumbs in a bowl, drizzle with 1 tsp olive oil, season with salt and pepper and stir to combine. Transfer the fish mixture to a 750ml (3 cup) baking dish and scatter over the breadcrumb mixture. Grill for 5 mins or until golden and bubbling.
Step 5 — Serve up
Meanwhile, combine 2 tsp olive oil and 1 tsp red wine vinegar in a large bowl and season with salt and pepper. Add the spinach and toss to coat. Divide the fish bake and spinach salad among plates and enjoy!
Step 6 — Make it milder
Our pepper and garlic seasoning has a mild peppery kick, so reduce the amount if you prefer less heat.