Preheat an oven to 160°c/140°c fan (320°f/284°f).
Peel the onion & carrot, finely dice then set aside.
Next, trim any sinew from the beef, cut into 1" pieces then season with a good pinch of table salt.
Place a large saucepan over a medium heat then add in the veg oil. Leave to warm up for a minute or so then add in half the beef.
Fry until seared on all sides then remove from the pan & transfer to a plate. Repeat with the remaining beef.
Next, add the diced veg to the pan & cook for 5-10 minutes, until they're just starting to soften.If necessary, add in another tbsp of veg oil when frying the veg. Stir in the grated garlic & chopped herbs, cook for 30 seconds then stir in the tomato paste. Cook for another 30 seconds then deglaze the pan with the Guinness.
Add the seared beef, beef stock & bay leaves to the pan then bring to a simmer.
Season with salt & pepper, cover with a heatproof lid (or foil) then transfer to the preheated oven & cook for 2-3 hours, until the beef is tender & soft.
Place the pan of beef over a medium heat, stir in the ketchup & Worcestershire sauce then bring to the boil. In the meantime stir together the cornflour with 3 tbsp of cold water.
Stir in the cornflour mix then cook out for 3-4 minutes, stirring regularly.Start by adding in half the cornflour then add in more as necessary. If the sauce is looking a little thick, thin it out with a splash of beef stock/water. Check the beef for seasoning, adding more salt & pepper if necessary then transfer to a shallow dish & leave to cool down.
Pick out the bay leaves then chill the beef in the fridge until completely cold. Give the beef at least an hour in the fridge or up to 2 days.