The rule of thumb for stocks is this: meat provides flavour and bones create body. Veal bones, like the one chef Emmanuel uses in his recipe, have large amounts of gelatin which produces a rich stock that gels when refrigerated.
The trick to good stock, he says, is low and slow. “It is simple, but a good stock requires time and attention to reduce, develop and gradually increase in flavour. At home, I simply allow the stock to slowly reduce overnight for a more intense flavour, and it also makes my house smell really nice in the morning.”
Once you’ve made a big batch of this stock, chef Emmanuel recommends freezing it in small individual packages (try ice cube trays) because they keep well in the freezer for a long time and you only need a small amount each time for sauces or seasoning.