Although tomatoes are not really vegetables, they are perhaps the single most common plant element of modern cuisine -- and for good reason. Tomatoes can be ripened at home by leaving them to rest at room temperature; upon ripening transition them to a refrigerator. Cooking strips tomatoes of many of their nutritional boons, but in any case they are a great source of vitamin C, vitamin E, folate, dietary fiber, and lycopene (prostate health).