Cut the steak into cubes.
In a large pan, heat up the oil, add the butter and allow it to melt.
Season the beef with salt and pepper, and brown it in batches.
Remove from the pan and set aside.
In the same pan, fry the peeled and chopped/sliced onion until soft, then add the garlic and carrot too.
Add the browned beef back to the pan together with the beef stock, bay leaves, Worcestershire sauce and tomato puree.
Give it a good stir.
Peel the potatoes, and use a mandolin to slice them (alternatively use a sharp knife to slice them thinly).
If the pan is not ovenproof, transfer everything to an ovenproof pan, and arrange the sliced potatoes over.
Cover with kitchen foil, and bake in the preheated oven at 170 degrees Celsius (340 Fahrenheit) for 50 minutes.
Remove the foil, increase the temperature to 200 degrees Celsius (390 Fahrenheit) and bake for a further 15 minutes until the potatoes and golden, and the beef and veggies are tender.
Garnish with fresh parsley if you like.