Heat 7.5ml of olive oil in a hot frying pan and sear the beef on both sides.
Fry shallots, red onion, tomato purée, and garlic in a casserole dish with remaining oil until browned.
Add the beef, 200ml stout, 200ml stock, and thyme, then season with salt and pepper.
Bring the liquid to a boil and simmer for 20 minutes.
Remove the beef and set it aside to rest while keeping it warm.
Mix 25g butter and 10g flour together and whisk into the boiling sauce to thicken.
Combine mashed potatoes with chives and parmesan to taste.
Serve the sliced beef with cheesy mash and spoon the gravy over the top.