It may sound a bit strange and unusual for some, but vinegar is a common ingredient in some soup recipes, and there is a good reason for it. If you think about it, vinegar is really a flavor-enhancer (umami). That's why it is so often used in cooking, sauces, and salad dressings. The same is true with soups.

You can also go with more heat and spices. "Ground paprika, turmeric, nutmeg, ground ginger, and other powdered spices add a touch of color and spiciness to broths," she says. As a general rule, use fresh herbs at or near the end of cooking and dried herbs and spices early on.