Before starting, preheat the oven to 450°F. Wash and dry all produce. Heat Guide for Steps 2 and 4 (dbl for 4 ppl): 1/4 tsp mild, 1/2 tsp medium, 1 tsp spicy and 1 1/2 tsp for extra-spicy! Cut tomato into 1/2-inch pieces. Cut potatoes into 1/4-inch rounds.

Add potatoes and 1 tbsp oil to an unlined baking sheet. (NOTE: For 4 ppl, use 2 baking sheets, with 1 tbsp oil per sheet.) Season with salt and 1 1/2 tsp Montreal Steak Spice, then toss to coat. (NOTE: Reference heat guide.) Roast in the bottom of the oven, flipping halfway through, until tender and golden-brown, 16-18 min. (NOTE: For 4 ppl, roast in the middle and bottom of the oven, rotating sheets halfway through.)

Meanwhile, add horseradish, mayo, mustard and 1/2 tsp sugar (dbl for 4 ppl) to a small bowl. Season with salt and pepper, to taste, then stir to combine.

Heat a large non-stick pan over medium-high heat. Meanwhile, pat barramundi dry with paper towels. Season with salt and 1/2 tsp Montreal Steak Spice. (NOTE: Reference heat guide.) When hot, add 1 tbsp oil (dbl for 4 ppl), then barramundi, skin-side down. Cook until skin is crispy, 4-5 min. Flip and reduce heat to medium. Cook until barramundi is opaque and cooked through, 2-3 min.**

Meanwhile, add vinegar, 1/4 tsp sugar and 1 1/2 tbsp oil (dbl both for 4 ppl) to a large bowl. Season with salt and pepper, to taste, then whisk to combine. Add spring mix and tomatoes, then toss to combine.

Divide salad, barramundi and potatoes between plates. Serve horseradish-mustard mayo alongside for dipping.