Every area should have its local great restaurant, and for Thornton Heath, this is Blue & Orange. I live in Thornton Heath, so I have visited this restaurant many times. For me, it is the best and most reliably good restaurant in South London.
The food is always excellent, we have eaten from all parts of the menu and it is consistently very good. The menu is varied with an Eastern Mediterranean inclination. The Borek is excellent as a starter and the Kulbasti is a fantastic main course. They also do pasta (the chicken liver tagliatelle is delicious), pizza and various hamburgers.
The chilli sauce is made on the premises and is really good – it is worth the trip for the chilli sauce alone!
Blue and Orange is fully licensed, the house beer is Efes. I have noticed recently that they are serving lots of cocktails with dinner, although to be fair, I haven’t tried one yet. It is open all afternoon as well as at night, so it is handy if you are looking to eat early or to have a late lunch.
It is probably worth ringing ahead to book if you are intending to go at peak times as it is usually pretty busy at night.
Heartily recommended!
Try the homemade chilli sauce!
The London Lark! 
Sounds wonderful.
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