Why do Onions taste sweet?

Once we start applying heat to onions, a bunch of things begin happen inside and out. There are (at least) six major transformations and reactions that are important to understand: 1. Evaporation 2. Cell wall breakdown 3. Aroma compound evolution 4. Maillard reaction 5. Caramelization 6 - Pyrolysis (that char!) Evaporation is one of the simplest, but most important as it concentrates the natural sugars for deeper sweetness. Check out the full deep dive!