Capers. They grow in many places of Greece and Cyprus, where the leaves (as well as the buds) are eaten fresh in salads. If they are the main ingredient, it's a καπαροσαλάτα (kaparosaláta), which is a specialty on Santoríni. Sometimes the leaves are preserved in salt, too.
On the islands you may also find stewed capers, κάπαρη μαγειρευτή (kápari mageireftí) made with onions, Mavrodáfni and olive oil. They are popular on Sífnos; on Santoríni they sometimes serve them with fáva.
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