What five-ingredient recipe actually taught you something?

Not just easy or tasty, but one where stripping things down forced you to understand what each element was doing. The kind where there was nowhere to hide, so you actually paid attention. Is there a five-ingredient recipe that made you a noticeably better cook, even if the finished dish looks humble?
Source: The Best $9 Trader Joe's Dinner And 10 Other Low-Effort Meals I Swear By (That Only Need 5 Ingredients Each) ↗