Heat the oven to 180C or 160C fan-forced. Brush a large ovenproof dish with a little olive oil.
Season the fish with salt and black pepper. Drizzle a little olive oil over the fish as well.
Put the tray in the oven and roast for 8–10 minutes until the fish is cooked through.
While the barramundi roasts, start preparing the potatoes. Scrub them, and either cut them in half or cut them in quarters, whichever way you fancy.
Then submerge them in a separate large ovenproof pan of cold salted water.
Add a drizzle of olive oil to keep them from sticking and bring them to a boil.
Simmer the potatoes for 10 minutes or until they are almost cooked; they should still have a slight crunch to them. Set aside.
In a large pan, add lemon juice and a drizzle of olive oil. Toss the lemon slices in the oil and herbs. Cook for a further 2–3 minutes.
Crush the garlic and put it in a pan with the lemons and their juices. Add the feta cubes.
Once the potatoes are cooked, add them to the pan along with the capers and onion. Toss all the ingredients together and add pepper to taste. Cook for a minute or two or until the onion is soft.
Drain the potatoes and lay them in the serving dish along with the fish.
Add the parsley, and pour the sauce over the potatoes and fish.
Serving Suggestions: Serve with a side of rocket salad and enjoy!