Preheat your oven to 180 C. You will need a deep oven proof pan with a oven proof lid, if no lid, just use foil.
Add salt and pepper to the flour and coat the cubed beef. Brown the beef in the deep ovenproof pan with a splash of olive oil. Remove the beef from pan.
Add a bit more oil to the same pan and cook the onions until translucent, then add the carrots and celery and cook for another 3-5 minutes, then add the garlic and cook for 2 minutes more.
Add in the tomato puree and rosemary and stir in, cook for a further 2-3 minutes. Add the chopped tomato and cook for 2 minutes. Add the red wine, simmer to reduce slightly. Add the beef stock and allow to reduce for about 10 minutes.
Cover the pot with a lid and place in the oven for 1 1/2 to 2 hours.
Remove from the oven and remove the lid or foil. Give the stew a quick mix, smooth out the stew and cover with thinly-chopped peeled potatoes, arranged so they are overlapping slightly. Drizzle with the butter, and season to taste with salt, pepper, and dried thyme.
Increase the oven temp to 200 C, leave the pan uncovered and place in the oven again and bake for another 45 minutes or until the potatoes are tender.
Remove from the oven, sprinkle the Gruyere cheese over the potatoes. Place the oven again for 5 to 10 minutes on until the cheese is bubbly.
Serve.