London, of course. Home to the most diverse restaurant scene in the world, IMO. I remember eating authentic Thai food, Indian, Sri Lankan, Burmese, Vietnamese, Cantonese, Turkish, Cypriot, French , Greek, Italian, Spanish and English (of course) last time I was there.
Memorable meals? Indian food at Moti Mahal in Covent Garden, prepared by the Indian PM's former chef. Busabai Thai food in Soho, Cay Tre ( a divinely cooked butter fish), also in Soho, Doner kebabs at midnight along the Tottenham Court Rd. Unusual Burmese food in the Edgeware Rd. Classic French Bistro fare at Zedel's, in Piccadilly, posh fish and chips in Mayfair and down to earth Scampi & chips in the Montagu Pyke, formerly the Marquee Club.
Lisbon: I spent very little time there, but had lunch in the Mercado, a huge warehouse type place with loads of gourmet restaurants. Cod with greens and potatoes, perfectly cooked.
La Asunción, Margarita. An invitation to eat at Langar, opened by my chef friend Sumito. I remember we had sardines and Barracuda with a mustard sauce.