Preheat your oven to 220°C/200°C Fan/Gas 7. Bring a medium pot of well-salted water to a rolling boil. Cut one large potato into generous wedges and carefully lower them into the boiling water. Parboil for 4 minutes until the edges are just beginning to soften — you want them yielding to a knife tip but still holding their shape. Drain thoroughly in a colander and allow the steam to escape for a minute so the surfaces dry out, which will encourage crispiness in the oven. — Shaking the colander gently after draining roughs up the surface of the wedges, creating more texture for the oil and seasoning to cling to — a trick for extra-crispy results.

Spread the parboiled wedges on a large baking tray in a single layer alongside the 2 unpeeled garlic cloves. Drizzle generously with olive oil (about 2 tablespoons), then scatter over the fresh thyme leaves and season well with salt and black pepper. Toss everything together so each wedge is evenly coated, then roast in the hot oven for 30 minutes, turning once halfway through. The wedges are done when they are deep golden-brown at the edges, crisp on the outside, and completely tender when pierced with a skewer. — Leaving the garlic unpeeled protects the cloves from burning; you can then squeeze the soft, sweet roasted garlic out of the skins and spread it on your ciabatta as an extra flavour layer.

About 10 minutes before the wedges finish roasting, prepare the burger. In a mixing bowl, combine 150g minced beef with the finely chopped quarter onion, a pinch of dried chilli flakes, and a generous seasoning of salt and pepper. Mix with your hands until just combined — overworking the meat will make the patty tough. Shape the mixture into a round, even patty roughly 2cm thick and rub the outside lightly with a little olive oil to prevent sticking. — Make a very slight indent in the centre of the raw patty with your thumb — this counteracts the natural puffing that occurs during cooking and keeps the burger flat and even.

Place a heavy frying pan (ideally cast iron) over a high heat and allow it to get smoking hot — you should see a faint haze rising from the surface. Lay the burger patty in the dry pan and fry for 4–5 minutes on the first side without moving it, letting a deep brown crust form. Flip once and cook for a further 4–5 minutes on the second side until cooked through, with no pink remaining in the centre and the juices running clear. — Resist the urge to press down on the burger with a spatula — this squeezes out the precious juices and leads to a drier patty.

While the burger finishes cooking, preheat your grill to high. Place the ciabatta slices cut-side up under the grill for 2–3 minutes until golden and crisp at the edges with a satisfying crunch when pressed. Place the hot burger patty on the toasted ciabatta base, add any desired toppings such as sliced tomato, lettuce, or mustard, and cap with the top slice. Serve immediately alongside the roasted thyme potato wedges.