Turkey produces lots of citrus fruit along its long Mediterranean coast. It is an important part of the Turkish diet.
Though the use of citrus fruits in Turkish cuisine is limited, use of lemon (limon; botanical name Citrus x limon) is used in many dishes as a condiment or flavoring. It is very common to see slices or wedges of lemon used for decoration, or placed on the sides of plates for the diner to use as desired. Lemon juice is widely used; grated lemon peel/rind less so, but it is used.
Soups may contain lemon juice, and a wedge of lemon is commonly served on the side for use as desired.
Salads are traditionally dressed with olive oil plus either lemon, vinegar (sirke) or pomegranate juice (nar ekşisi). For simple salad vegetables (tomato, cucumber, etc.) with no dressing at all, ask for söğüş (sew-EWSH).
That Turkish favorite, stuffed grapevine leaves (yaprak dolması), in the version made with olive oil (zeytinyağlı) and without meat and served unheated, uses lemon both in preparation and as a garnish. Also, the delicious eggplant/aubergine purée (patlıcan ezmesi) is flavored with a bit of lemon juice.
Seafood dishes very often contain lemon juice.
There are other examples of lemon juice lurking unseen in prepared dishes. Grilled meats, including döner kebap, may be prepared in a marinade containing lemon juice, or dressed with a bit of lemon juice after cooking. When ordering, specify "no lemon juice."
It may be that chicken dishes are less likely to have lemon used in their preparation.
Many Turkish stews are made with a base of mutton broth and tomatoes, so lemon is not commonly used as an acidic additive in these, although this may depend on each chef.
Except for lemon, it should be easier for you to avoid most citrus fruits, as they are usually visually identifiable. Oranges (portakkal) and grapefruits (greyfurt) are juiced, included in fruit salads, or simply peeled and eaten as-is. Mandarin oranges/tangerines (mandalina) are used in the same way. However, citrus fruits may show up in some confections, such as Turkish Delight (lokum).
There is no general term in everyday Turkish for "citrus fruits." The scientific name, turunçgiller meyve ("fruit of the bitter orange [turunç] family"] is unlikely to be familiar to restaurant staff. So you can ask:
İçinde limon suyu var mı? (EECH-een-DEH lee-MOHN soo-yoo VAHR muh, "Is there lemon juice in it?")
Yes = evet (eh-VEHT)
No = hayır/yok ('higher,' YOHK)
Limona ve portakkala alerjim var. (lee-MOHN-ah veh pohr-takk-KAHL-ah ah-lehr-ZHEEM vahr, "I'm allergic to lemons and oranges.")
Limon, portakkal, greyfurt, turunç ve benzeri meyve hiç yeyemem, alerjim var. (lee-MOHN pohr-tahk-KAHL GREY-foort tooROONCH veh behn-zeh-ree mey-VEH HEECH yeh-YEH-mehm ah-lehr-ZHEEM vahr, "I cannot eat lemon, orange, grapefruit, bitter orange or similar fruits, I am allergic to them.")
Most processed food
packages in Turkey contain lists
of ingredients, often in several
languages, but you may want to have
speaker help to interpret
the ingredients list.