Banana flowers (a.k.a. banana blossoms) are, as the name suggests, the blossoms from a banana tree. Like bananas, they are wonderfully edible.
Where to Get Banana Flowers
In areas where bananas grow, banana flowers are sold at farmers markets, road stands, and even grocery stores. If you're not in a tropical locale resplendent with banana trees, you may find banana flowers at Asian food stores or specialty markets, but usually only in the frozen foods section.
Note that banana flowers are different from banana leaves, which are heartier and thus more widely available. Banana leaves are not so much edible as they are used in many cuisines to wrap food for gentle cooking.
How to Eat Banana Flowers
The darker, tough husks on the outside simply need to be stripped away to reveal the tender, yummy yellow-green leaves inside. The youngest specimens can be simply chopped and used in salads (like this Banana Blossom Salad). Banana flowers can also be used in soups (like this Banana Flower Soup) or sliced and added to stir-frys.
Tips for Using Banana Flowers
Note that banana flower leaves will turn brown or black if left to sit exposed to air for any length of time. So after you remove the tough outer layer and separate or chop the inner leaves, put them in a bowl of acidulated water (add several tablespoons of lemon juice or vinegar or a bowl of water) to minimize the browning.