Near the Central Square, there are many places for quick bites, especially in the direction of the Sycamore Tree or Hisham's Palace.
It worth a visit to Qurantal mountain where Jesus fasted 40 days and 40 nights after the devil's temptation to him, where you will find a very nice restaurant at the bottom of the mountain, you will have your lunch in front of an amazing panaromic birds eye view of Jericho city ,the mountains of Jordan and the Dead Sea.
You can reach this restuarant by using the Cable Car of Jericho, it costs ~$15 55 NIS / Person for a 7 mintues trip of about 1.35 Km.
Jericho is famous for its tasty fruits, especially bananas!!