Heat a tbsp of oil in a large frying pan and fry the onion for 5 minutes until it starts to soften, then add the garlic to fry for a couple more minutes. Leave to one side to cool.
In a large mixing bowl, mix the beef mince, onion and garlic, egg, mustard, cayenne and breadcrumbs. Season your mix generously with salt and pepper, then divide the mixture into 4.
Shape each portion into a large patty, then add a tbsp of Guinness Cooking Paste to the centre of each.
Now form the mix very carefully around the paste until it’s fully encased in the burger, then chill for around 30 minutes to set into shape.
Take your burgers out of the fridge & heat a large frying pan with a little oil and add the burgers when the oil is almost smoking - fry for 4-5 minutes on each side until the burgers are coloured, then place them into an oven at 180C on a lined baking tray for 15 minutes - the paste might start to ooze a little out of the burgers, they don't have to be perfect!