Worcestershire sauce is a fermented English sauce, used as a condiment to enhance the flavor of various dishes. It is made from a blend of ingredients including malt vinegar, molasses, anchovies, tamarind, onions, garlic, sugar and spices. After fermentation, the sauce is aged, which gives it its complex flavor, at once salty, sweet and sour, and of the sea.

Worcestershire sauce is commonly used in marinades, meat sauces, soups and stews, and is a key ingredient in some preparations like Bloody Marys. Although naturally gluten-free per se, some commercial versions may contain malt vinegar made from barley, which contains gluten. So it's important to check labels to make sure it's gluten-free.

If you don't have any, you can replace it with a mixture of vinegar, smoked paprika and fish sauce.