Indonesian food is never pricey so for an expensive night out go to William Kafe Artistik, run by one of Indonesia's top gourmands, William Wongso. One has to book a couple of days in advance, which is when one plans the menu as each meal is made specially. The result is likely to be an amazing Asian-Western fusion meal. Food alone will be about £40pp. Drinks could easily see that double.
Jalan Panglima Polim Raya 63-65
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I would describe William W as a gourmet not a gourmand, though I suppose he could shed a few kilos (and so could I).
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