Preheat your oven to 220°C/200°C fan/gas mark 7. Remove the lamb steaks from your fridge to allow them to come up to room temperature.
Bring a large saucepan of water with 1/2 tsp salt to the boil for the potatoes.
Once boiling, add the potato slices to the water and simmer until just tender, 8-12 mins.
Meanwhile, trim the green beans. Halve, peel and thinly slice the red onion. Peel and grate the garlic (or use a garlic press). Pick the rosemary leaves from their stalks and roughly chop (discard the stalks).

Once the potatoes are cooked, reserve some of the potato cooking water (see ingredients for amount), then carefully drain into a colander.
Heat a drizzle of oil in a large frying pan on medium heat. Once hot, add half the garlic and cook until fragrant, 30 secs.
Add the creme fraiche, chicken stock paste, reserved potato water, rosemary and half the cheese. Mix together, bring to the boil, then remove from the heat. Season to taste.
Lay the cooked potato slices in layers in an appropriately sized ovenproof dish, then pour over the creamy sauce. Sprinkle the remaining cheese on top. Bake on the top shelf of your oven until golden brown and bubbly, 15-20 mins. TIP: Put the dish onto a baking tray to catch any drips.

When the dauphinoise has 10 mins of cooking time left, wipe out your frying pan and put on high heat with a drizzle of oil.
Once hot, lay the lamb steaks into the pan, season with salt and pepper and fry until browned all over, 8-10 mins total (for medium-rare). Turn every 2 mins. TIP: Cook for 2-3 mins extra if you like it more well done.
When cooked, transfer to a plate and leave to rest, covered loosely with foil. IMPORTANT: Wash your hands and equipment after handling raw meat. The lamb is safe to eat when the outside is browned.

Meanwhile, heat a drizzle of oil in another frying pan on medium-high heat.
Once hot, add the green beans and stir-fry until starting to char, 2-3 mins. Stir in the remaining garlic, then turn the heat down to medium and cook for 1 min.
Add a splash of water and immediately cover with a lid or some foil. Allow to cook until the beans are tender, 4-5 mins.

While the beans cook, heat a drizzle of oil in the (now empty) steak pan on medium heat.
Once hot, add the onions and fry until softened, 2-3 mins. Pour in the water for the sauce (see ingredients for amount), then bring to the boil on high heat. Stir in the red wine jus paste, then reduce the heat to medium.
Allow the sauce to bubble and thicken, stirring regularly, 5-6 mins, then remove from the heat.

When everything is ready, slice the lamb steaks widthways and share between your plates. Serve with the dauphinoise and garlicky beans alongside.
Spoon over the red wine jus to finish. Enjoy!