Fried green tomatoes are popular in the Southern United States and made from green tomatoes (unripe tomatoes that is - some varieties are green when they're ripe!) and coated with cornmeal and fried.
In the UK cornmeal is available in health food shops and is sometimes found in the supermarket called maize meal or polenta.
Traditional preparation of fried green tomatoes begins by cutting the tomatoes into approximately 1/4-inch slices. They are then seasoned with salt and pepper, coated with plain, coarse cornmeal, and shallow fried in bacon fat for a few minutes each side, or until golden brown.
Shallow frying is preferred, as the tomatoes do not float in the oil, which allows the weight of the tomato to press the cornmeal to the underside of the tomato.
Alternatives include using breadcrumbs or flour instead of cornmeal, and frying in vegetable oil or other fat.
The sliced tomatoes may be dipped in a beaten egg before the cornmeal is added which helps the cornmeal stay in place during the cooking process.
Information from wikipedia.org.