Avocados are not the only fruit you might think is a vegetable. While the These include cucumbers, peppers, tomatoes and string beans. Here are the top 10 fruits that are commonly mistaken for vegetables (I think find out that only 52% of people surveyed correctly identified the tomato as a fruit. Just over one in ten people were able to correctly identify the avocado as a fruit. Grafting: the secret to great fruit and vegetables In an avocado or olive, the seed is the stone at the centre. 10) Tomato - 52 per cent.