Once the stew has come to a simmer, cover with a lid and transfer to the preheated oven.
Cook the stew until the meat is fork tender. This should take anywhere between 2 to 5 hours. This all depends on how high the temperature of the oven is.
After about 1 1/2 hours, it's a good idea to check the stew for doneness. The dish should be cooked until the meat is completely fork-tender.
Once done, remove the stew from the oven. At this point, you can proceed to serve the stew now; however, we recommend that the stew be cooled and chilled overnight for the best flavor development.
If chilling overnight, for food safety reasons, it's best to cool the stew quickly. To do this, place the pot over an ice bath and gently stir from time to time to bring the temperature down. Once cool, cover and transfer to the refrigerator overnight. To prepare the dish for serving, first remove any hardened excess fat from the surface of the stew.
Next, place the stew into a preheated oven (see note from Step 2) between 200° F to 350° F (or 95° C to 175° C). While the stew is reheating, you can prepare the onions and mushrooms.