不瘟不火 [－－－－]

Jyutping bat1 wan1 bat1 fo2
Pinyin bù wēn bù huǒ

Definitions (Wiktionary)
  1. phrase, idiomatic, of a performance
    neither dull nor overpowering; just right
Definitions (Kaifangcidian)
  1. （沒有對應漢語詞彙）