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The Feynman Technique is a four-step method: pick a concept, explain it as if teaching a child, find the gaps where your explanation breaks down, then go back to the source. The gaps are the honest map of what you actually know. I use it before any exam or technical interview: not to rehearse the right answer, but to identify where my model of a concept is shallow. The test is not 'can I recite the definition' but 'can I explain the mechanism in plain language without jargon'.
The part that surprises people: using simple language is harder than using jargon. Jargon is a way of deferring explanation. When you force yourself to use plain English, you discover whether you actually understand the concept or just recognise the vocabulary around it.
This applies directly to technical writing. If a sentence in a README or a comment requires domain knowledge to parse, it is probably shallow. The goal is for a future reader (or future me) to understand the mechanism, not just recognise that one was in play.