If you cook it in one chunk until tender, then remove and cut into reasonable pieces. Or if you are using beef cubes right from the start, brown first, then add onion and garlic and enough water to cover bottom of pan and only half way up the meat. Keep adding a little water or broth until almost tender. Then add the rest of the needed liquid and veggies and simmer slowly. The meat needs to be braised to make it tender. If it's in a big vat of water/broth from the beginning of the cooking process, you've boiled the meat and it gets tough. Years ago this wasn't always the case, but now the meat is so lean.