Preheat an oven to 150°c/130°c fan (300°f/265°f).
Next, cut the onions & celery into a medium dice & cut the carrots into a large dice (1-2cm in size). Mix the veg together & set aside.
Pour the vegetable oil into a large saucepan & place over a high heat. Whilst the pan is heating up, season the short ribs all over with salt.
Carefully place the short ribs into the hot oil & sear well on all sides.
Once seared, remove the ribs from the pan, transfer to a plate & set aside.
Add the diced veg into the pan & cook until softened, stirring almost constantly. This will take around 4-5 minutes.
Stir in the grated garlic & cook for a further 30 seconds.
Next, add in the tomato paste, stir to coat the veg then deglaze the pan with the Guinness.
Add in the beef stock, the seared beef ribs & the herbs. Season with salt & pepper then bring to a simmer.
Cover the pan with either a heatproof lid or foil then place in the preheated oven. Cook for 2-3 hours or until the beef is tender & starting to fall off the bones. Once cooked, remove the short ribs from the sauce & set aside.Pick out the bay leaves & any herb stalks from the sauce then set the pan over a medium heat & bring to a boil. In a bowl, stir together the cornflour & 2 tbsp of cold water. Pour into the sauce along with a couple of drops of gravy browning, mix to combine then cook out for 2-3 minutes.
Stir in the Worcestershire sauce & season with salt & pepper then take the sauce off the heat.
Pull the meat off the short ribs, discarding any bones & sinew then mix into the sauce with the chopped parsley. Transfer the stew into a large heatproof dish & set aside.