You could call me biased, given this is the 3rd Highbury restaurant in my list, but if you're doing so then you've clearly never tried the Biang Biang Noodles at this unassuming little BYOB gem
If you want a peaceful day out of the busy city, Highgate doesn't really feel like London. The cemetery is interesting and peaceful, there's a tour of the old half which is definitely worth the money. Karl Marx, among others are buried there.
Morito is a few doors down from it's well know sister restaurant Moro. This not long open tapas restaurant feels like it could be in a little back street in Barcelona. The food is great, and it has a buzzy but relaxed atmosphere. You might need to wait a little while for the table, but I promise it's worth it.
Sans Pere is my new favourite place to have breakfast, café or lunch. In the heart of Shoreditch it really feels like a modern home. Their quiches are delicious and they have an in-house patisserie kitchen and let me tell you their cute bite-size choux and bronuts (brioche-donuts) are worth the detour.
Being an East London boy at heart I am partial to an occasional fix of café culture. Pellici's has been running since the start of the last century, to which me, my father and my father's fathers have all enjoyed its mix of tasty Italian/London grub and energetic atmosphere. If you're visiting, make sure you drop by, as it will provide a valuable, forever-depleting education into what East London is really all about.