Heat the oven to 140C/fan 120C/gas 1. Fry the ox cheek in 1 tbsp oil in a large, heavy pan over a medium heat. When browned, remove from the pan and add the vegetables, bay leaves and thyme. When all the vegetables are golden (about 8 minutes), add the ale and scrape away any bits stuck to the bottom of the pan. Add the ox cheeks back and simmer until the liquid has reduced by half. Add the stock, bring back to the boil, and cover with foil or a tightly fitting lid. Slow-cook in the oven for 4-5 hours, until very tender. Turn the meat every 2 hours while cooking.