Rescues · TO BOIL
Vegetables are drab and grey.
Why it happens
Boiled too long. Chlorophyll degrades with prolonged heat and acid; brief boiling keeps green vegetables green, extended boiling does not.
Recovering it
Overcooked pasta cannot be undone, though shocking it in cold water at least stops it going further. Grey vegetables are a colour loss only. Stuck pasta separates somewhat if returned to hot water briefly and stirred. The most useful habit is reserving a cup of the cooking water before draining anything — it is seasoned, full of starch, and the single most useful thing to have on hand when a sauce needs loosening or binding.
The mechanism
At normal pressure water tops out at 100°C however hard it boils, so more heat under a boiling pot makes it boil faster, not hotter. What a rolling boil provides that a simmer does not is movement: it keeps pasta separated so it cannot glue itself together, it circulates heat so a large pot has no cold spots, and it supplies the energy that fully gelatinises starch in a thickening slurry. Salting pasta water is not about raising the boiling point — the effect at kitchen concentrations is a fraction of a degree and irrelevant. It is the only opportunity to season the pasta itself, and the dissolved starch that comes off into that water is a genuinely useful emulsifier. Less water gives a more concentrated starch solution, which is why the traditional advice to use a huge pot is worth ignoring for most sauces.
The full TO BOIL lesson — how to tell, where to practise it, what it carries to.