the most basic of basics; the absolute fundamentals
Emphasizes that something is the most fundamental, essential, or elementary aspect of a subject. Often used in teaching, training, or when stressing the importance of mastering the basics.
The most basic of basics in cooking is how to use a knife.
Safe driving is the absolute fundamental.
A set phrase formed by 基本 (basics) + 中 (among) + の (possessive particle) + 基本 (basics), literally 'the basics among basics', emphasizing the most fundamental level.