Place your beef into a pot (remember it has to be big enough to accommodate the vegetables as well), cover with water, and add your herb bundle, celery, bay leaves and peppercorns. Bring up to the boil, skim, and reduce to a very gentle simmer, with barely signs of movement in the water, for approximately 4 hours. Prod with a knife to check how the meat feels—it should be giving, but not collapsing!