Use a lean beef cut that will casserole well, chuck, blade or oyster.
For 4 good servings you will need about 1kg of beef cut into 1-2cm cubes
In a large saucepan, or preferable an oven casserole dish that can be put on the top of the stove as well as in the oven. Heat up a couple of tablespoons of good quality olive oil until sizzling. Fry off the meat in batches - just enough at a time to cover the base of the pan, brown well all over , remove and repeat until all the meat cubes are seared and sealed - DO NOT STEW - if they do - start again with fresh oil!
Lower the heat then fry off 8/10 pickling onions until golden (or 2/3 larger onions cut into big wedges). Sprinkle about 2 tablespoons of Plain flour into pan and stir to thicken remaining juices then return to the pan the browned meat.
Finish off with a good handful of chopped fresh parsley - a good grind of black pepper - a hearty slosh of Worcestershire Sauce and of course Guinness (about 330ml) and stir to deglaze the pan, then add the browned meat and combine well.
(You can also add large diced carrot or any other root vegetable or/and some diced garlic, at the same time as the onion and also a tablespoon or two of tomato paste just before you put in the flour).
Pop the lid on the casserole and place in a 180c oven for about 1 ½ hours.
Transfer the casserole contents to a pie dish and top with your favourite pastry, shortcrust, puff or whatever. Return to the oven to cook the pastry.
Want to make it richer - before placing in pie dish add another 100ml of Guinness; even a couple of really good slurps of H.P. sauce or go the full Irish and pop some oyster flesh on top of the meat just under the crust.