Baalbek has a handful of restaurants near the ruins and around the main square, most serving Lebanese standards — grilled meats, mezze, fresh bread, and local produce from the Bekaa Valley. The valley grows an abundance of vegetables and is also Lebanon's main wine region. Expect simple, generous cooking rather than anything sophisticated.
Look for restaurants serving kibbeh nayyeh (raw lamb with bulgur, herbs, and spices), which is a Bekaa Valley speciality, and fattoush with local herbs. Fresh arak (the anise spirit) is widely available and goes naturally with a mezze spread.