Spaghetti Aglio e Olio

Method

1. boil9 min
   well salted, less water than usual, to 2 minutes short of the packet
   pasta, reserving two cups of the water before draining. Use only enough water to cover — less water means more dissolved starch per cup, and that starch is the emulsifier the sauce depends on. Undercook deliberately; it finishes in the pan
2. saute5 min
   cold oil, cold pan, medium-low, garlic added at the start
   olive oil + sliced garlic + chilli flakes, brought up slowly until the slices turn pale gold at the edges and smell sweet and nutty. Starting cold gives the garlic time to release its aromatics into the oil before it colours. Garlic browns hard around 150°C and the bitter compounds it makes then do not cook out — if it darkens, throw it out and start over rather than build on it
3. emulsify4 min
   drained pasta into the oil, half a cup of pasta water, high heat, tossing constantly
   pasta + garlic oil + pasta water, tossed hard until the liquid goes from thin and separate to a glossy sauce that clings. The starch dissolved in the water coats the oil droplets and holds them suspended; the tossing supplies the mechanical energy. A pan left to sit will not emulsify however long it cooks — the motion is the technique
4. fold1 min
   off the heat
   + parsley (+ pecorino, + pepper), tossed through. Cheese goes in off the heat and with the pan slightly cooled; dropped into a boiling emulsion it seizes into strings
5. season1 min
   immediately, plates warmed
   to taste, loosening with more pasta water if it tightens — and it will keep tightening as it cools, so send it slightly looser than looks right. There is no salt in the sauce itself; all of it came from the water the pasta cooked in, which is why that water has to be properly salted