Onion is an underestimated ingredient. Most people I know get excited over garlic, but onion? Well, onion is just as magnificent as garlic if cooked correctly. Allowing onion to caramelize is one way of maximizing its flavors.Vegetable broth is used here as it makes a tasty but light gravy. You may substitute chicken or beef broth but know that the flavor and aroma of the gravy will be heavier.