use an instant read meat thermometer. the meat needs to reach an internal temperature between 210 & 220 degrees farenheit. that's when the collgen breaks down & it becomes tender & falling apart. anything less than that & you are looking at a tough hunk of meat. depending on the size & shape this could take from 2 1/2 to 4 hours. cook low & slow & with some liquid. I second the onion soup mix method. I mix mine with tons of garlic, some canned tomatoes & red wine.