Preheat the oven to 220C, fan-forced. Line a large oven tray with baking paper. Quarter the unpeeled potatoes. Put the potato and 1 unpeeled garlic clove on the lined tray. Drizzle with 2 tsp olive oil, season with salt and pepper and toss to coat. Bake for 15 mins, then remove the garlic from the tray.
Step 2 — Prep ingredients
While the potato and garlic are baking, trim the beans and cut in half. Finely chop the pistachios. Combine the pistachios and South American seasoning in a bowl.
Step 3 — Finish tray bake
Pat the fish dry with paper towel. Add the fish, skin-side down, to the tray with the potato. Drizzle the fish with 2 tsp olive oil and press on the pistachio mixture. Bake for 3-4 mins. Add the beans to the tray and drizzle with 2 tsp olive oil. Bake for a further 3-4 mins until the fish is cooked through (see Kitchen 101) and the veggies are tender.
Step 4 — Make caper sauce
Meanwhile, coarsely chop the capers. Squeeze the roasted garlic from the skin into a bowl and mash with a fork. Add the capers, 2 tbs mayonnaise and ½ tsp white wine vinegar. Season with pepper and stir to combine.
Step 5 — Serve up
Divide the fish and veggies among plates. Serve with the caper sauce and enjoy!
Step 6 — Kitchen 101
Cooking times may vary depending on thickness of fillets. To check if your fish is cooked through, simply use a fork or the tip of a knife to take a peek inside the thickest part of the fish; if it comes apart easily, the fish is cooked.