Brixton Village and Market Row
The strength of this indoor food court is in variety: here you can start with classic barbecue or pizza, go to Japanese okonomiyaki, eat traditional komidas corrientes and empanadas paisas (taking pity on those who do not know much about Colombian cuisine: it is fried meat with rice and beans, and not sweet pancakes). And to complete this marathon - have a cup of good coffee with a slice of an exciting cake.
Berwick Street Market
Do not let Soho deceive yourself: in the midst of the noisy sellers of flowers, fabrics and fruits (Soho market is 300 years old! can you imagine that!?) there are plenty places where you can have breakfast, lunch and dinner. Often there may be nowhere to sit down and you can get stuck in a line consisting mostly of locals, but falafel, burrito or Greek souvlaki are worth to eat them on the go.
This exemplary hipster place is so popular that after 19:00 you will have to give £3 just to see how other people eat. But it will not last for a long time, because it is impossible to watch people eating such tasty food: spicy wings, sweet and sour ribs, salted donuts and a few bars with craft beer and complex cocktails will make you an accomplice.
Bang Bang Oriental
The huge food court of Pan-Asian food in the non-obvious for culinary entertainment district of Colindale is the largest not only in London, but, perhaps, throughout Europe. Just imagine: three dozen restaurants of Chinese, Japanese, Vietnamese, Korean, Taiwanese, Malaysian, Indian and Singaporean cuisine offer all the best at once. Here you need to try dimsam, bibimbap, congee and noodle soup with fried duck. Rather far away (of course, depends on where YOU live), but it is worth spending time on it.