you’ll need about 5 liters of water, salt, a kilo of onions, half a kilo each of celery and carrots. And you’ll also need lots of time – lots. The first step is to put the bones in a large baking dish and place them in a preheated 200 °C oven for about a half hour. In the meantime, wash and roughly cut the vegetables. When the bones are ready, transfer them to a pot, eliminating the fat, and place them in a liter of water. When the water comes to a boil, skim the bottom with a wooden spoon, freeing all the tasty residue so that it floats freely. Then add the vegetables, a handful of salt and wait until the water boils again. When foam begins to appear, skim it off the top.
Let the broth boil for at least 5-6 hours, adding water when it evaporates. When the broth is ready, pour it through a strainer into another large container and let it cool to room temperature. At this point, the broth can be stored in the refrigerator.