ISTANBUL (Reuters) - Istanbul’s beloved fish sandwiches, a staple street food in the Bosphorus city, are being offered for free to Turks who heed President Tayyip Erdogan’s call to sell their dollars for lira.

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The offer is just one of many by vendors across Turkey who are backing Erdogan’s appeal to nationalist sentiment, giving out anything from orchids, petrol or a three-day hotel stay for those who show dollar exchange receipts.

If customers can show a slip proving they exchanged $100 dollars into Turkish lira, Adnan Celiker, an Istanbul restaurateur, will hand over his fish sandwiches, or “balik ekmek”, for nothing.

“The aim here is to make our voice heard and show our reaction,” said Celiker, who runs a waterfront store on the Anatolian side of Istanbul where diners can enjoy their meal sitting on a nearby boat.

Celiker’s restaurant’s Facebook page touts the offer with a picture showing a raised fist emblazoned with the Turkish flag above a cowering $100 bill.

Erdogan has called on people to support the weakened lira by exchanging gold and foreign currency, citing an “economic war” being waged against Turkey.

The lira hit a record low of 7.24 to the dollar this week after losing nearly half its value this year, as investors fretted over Erdogan’s influence over monetary policy and a dispute with the United States.

It has since pulled back a little to under 6 lira to the dollar.

Despite the lira campaign, foreign currency deposits held by local investors in Turkey rose by $1.3 billion to $159.9 billion last week, central bank data showed on Thursday.

Turkish media have given extensive coverage to anti-U.S. protests, including videos on social media showing Turks apparently burning dollar bills and destroying iPhones.

A barbershop in eastern Turkey announced it will stop offering “American style” haircuts. The hashtag “Boycott USA” was the number one trending topic on Thursday morning and, later, “Turkey Will Prevail.”

In Istanbul’s Iskiklal Street, a popular tourist district, a group of men strummed the saz, a long-necked lute, and sang in front of Turkish flags. “America you exploited us for years,” they sang. “America the murderer, America the murderer.”