Fennel, also known as sweet anise, has a mild, sweet flavor that is similar to licorice. Popular in Italian and French cooking, fennel is used both as a spice and as a vegetable. There are several substitutes for this plant.
The fennel bulb and seeds are both used in cooking. The bulb and stalks are often used as a vegetable while the seeds are used as an herb. In Italian cooking, it is a popular herb added to meat balls and sauces but it also goes well with fish and seafood.
Anise seed can be used as a substitute for fennel as it also has a licorice flavor. Anise seed has a stronger flavor than fennel so less is needed if using this substitution. Cumin, caraway seeds and dill are also used as substitutes for fennel.
If you are using fennel as a vegetable in a dish, there are several substitutions. You can use bok choy stems or celery stalks, although celery cooks faster. If you want to duplicate only the taste of the fennel vegetable and not the volume in the dish, you can also use a teaspoon of fennel seed for each pound of fennel bulb called for in the dish.
References and ResourcesGormet Sleuth, The Gormet Food and Cooking Resource: Fennel bulb
The Cook's Thesaurus: Global Spices