expression, ichidan verb
have a discriminating palate; be particular about food
Describes someone whose taste in food has become refined through experience, often implying they are hard to please. Similar to 口が肥える, but 舌 emphasizes the sense of taste.
See also: 口が肥える
彼は世界中の料理を食べてきたので、舌が肥えている。
He has eaten cuisine from all over the world, so he has a discriminating palate.
It's a flavor that can satisfy even people with refined tastes.