敲硬核桃

qiāoyìnghétao ㄑㄧㄠ ㄧㄥˋ ㄏㄜˊ ˙ㄊㄠ

    • to tackle a tough problem head-on
    • to meet toughness with toughness

Character by character

Saying俗语俗語

Idiom惯用语 · Rarely used now

Literally
crack a hard walnut
Meaning
To face a tough problem head-on and meet toughness with toughness. Approving.

Sources