Jus, refers to the juices that are given up by meat during cooking.
To make it, skim fats and enhance with wine or port, rosemary and redcurrant jelly for lamb dishes. Try brandy, star anise, orange segments or mango and freshly squeezed orange juice with duck. Calvados and bramley apple work with pork and goose. For beef, roast a whole head of garlic, intact for around an hour in a low oven and squeeze out the cloves. For sunday roasts, add flour and gravy salts to the roasting tray, and stir continuously. Add vegetable stock or water from vegetables, following the principles in the stock recipe. Thicken to your preferred consistency.
Season. Try adding acids such as vinegars and citrus juices as a seasoning in jus. Add acidic liquids to lift the flavour profile, they can help loosen the sticky goodness that meat gives up from the base of the pan.
Sieve. You are looking for a smooth, clean sauce, you can always add aromatics such as star anise back later, for presentation.