Place the diced beef in a bowl and toss with the flour, salt and pepper until well coated.
Heat the olive oil in a large heavy bottomed saucepan or dutch oven and brown the seasoned beef, in batches if necessary, until nicely browned.
Add in the onion and continue cooking for a minute or two before adding the other vegetables and herbs.
After a few minutes add the Guinness, use this to scrap any crusty bits off the bottom of the pan. Throw the tomatoes in and bring everything to a boil.
Cover and simmer for about 2 hours until the meat is really tender and you have a lovely thick sauce.
Preheat your oven to 190°C.
Ladle the stew into your chosen pie dish (I used a large one, but small single serving dishes also work well).
Cut out the necessary shape from the puff pastry to put a lid(s) on your pie dish(es). Brush the egg wash around the edges before placing the lid on and squashing it down around the edges.
Lightly score a crisscross pattern with a knife on your pastry lid and then brush more egg wash over the top.
Place in the preheated oven for about 45 minutes until the puff pastry is lovely and golden.
Serve by itself or with some sides like steamed greens and mash.