Where? It depends. If you don't mind splashing the cash, I'd say go to his high-end restaurant Nopi, near Picadilly Circus. If you are a bit tight with your budget but still would like to try something new, then you've got 3 more options to choose: Islington, Notting Hill and Belgravia. They first one is a restaurant and the other two are a deli, which is an excellent option for lunch time.
Why? Oh dear, where to begin. For those who are not living in the London Bubble, you need to know that Ottolenghi is God over here. A renowned israeli chef that has brought to England a contemporary way of cooking. His style, known by mixing Middle Eastern cuisine (including Sirian, Turkish, Lebanese, Iranian, Israeli and Armenian) with Western style food, is great. A perfect combo, as I say.
As a newbie in the City, I went to Ottolenghi few months ago, completely unaware of the relevance of my dinner. But the minute you get into one of his restaurants, you clearly see you are going to have more than just a meal. It's a whole new experience. The restaurant in Islington (which is the one I went to) has a deli counter at the front, welcoming you to see what you can indulge for supper.
The menu is not vast but is more than enough. I like things kept simple. I suggest you to go with few friends so that you can to try as many dishes as you can. Since the portions aren't super big, I think sharing plates is the way forward. Although it took us a bit too much to be served, the wait was SO worth it.
My top 3 from the kitchen where the braised octopus with kalamata olive puree, mustard seeds, harissa and cavolo nero; (ii) the seared fillet of english beef with sweet coriander-mustard saucethe and (iii) the Seard duck breas with red cabbage puree, pickeled celeriac, date & walnuts. My mouth is watering just thinking about it!
As for my veggie favs I'd definitely go for the roasted aubergine with walnut yoghurt, herbs and spicy walnuts (see picture below) and the couliflower, onion, turmeric parsley and coriander fritters with chilli jam yoghurt.
Don't forget to have some bread with your meal (there's an excellent range) and eventhough you might be full by dessert time, you HAVE TO have dessert.
O.M.G. Desserts. I keep dreaming of them. But if you have to go for one, please try the passion fruit meringue tartlets. I wish I could have one of those everyday for the rest of my life. SO GOOD.
When? They are open Monday to Sunday, although opening times vary depending on the restaurant. Both Nopi and Ottolenghi Islington close their kitchens by 10,30-11pm (Mon-Sat), while the delis in Notting Hill and Belgravia usually close by 8pm.
So regardless of the timing, don't forget: BOLD.BIG.DELICACIES. A complete cultural explosion in the kitchen that is not to be missed.
P.S: the pictures have been edited by me but have been collected from Ottolenghi's site and other sources, as I was unable to take pictures when I went there!