I've been trying out an energy saving cooking technique lately, and it's been working great for us. It consists of boiling our dried pasta for only a fraction of the recommended cooking time, and then turning off the heat and letting the pasta "coast" to doneness. It works well when I bring the water back to a boil after the pasta is added and give it a few good stirs to make sure the noodles won't stick to each other. This takes just about three minutes and then the burner is turned off. I find that the noodles generally need one more minute to cook than they would if the pot were kept boiling.
For instance, last night I made a batch of my pumpkin-sage pasta (with dehydrated pumpkin from last year's garden). I brought the water to a boil, added the fusilli, stirred well, and set the timer for three minutes. Just before those three minutes were up, I gave everything another good stir while it was boiling. At three minutes I killed the gas, and covered the pot with a towel. The package said the pasta needed nine minutes of cooking time altogether, so I set the timer for seven additional minutes of coasting. The pasta came out perfectly cooked to our taste.
I'm pretty sure I heard of this cooking method from several different sources before I tried it. The English have a dish called "crimped shrimp" in which shrimp are added to hot liquid and then the pot is covered and removed from the heat. I believe the method is specifically mentioned for pasta in the highly enjoyable Depression Cooking with Clara series. If you haven't seen any of the episodes with this 93-year-old home cook yet, it's well worth checking out for some seriously frugal cooking suggestions. There are probably other dishes that could cook by coasting too.
I'm not sure how much of the total energy is saved by this method, but I would guess it's somewhere in the neighborhood of one-quarter. Obviously, the most energy is used to get the water up to boiling in the first place. Keeping it boiling after adding the pasta is probably relatively cheap. Still, this technique saves me six minutes of running the burner, so that's something. It's also less likely that the pot will boil over, which means less cleanup. And it only takes one additional minute to cook everything. This is an especially useful trick now that the weather is warming up and the house is hot in the evenings. Less heat added to the house in the process of cooking dinner. Try it and see what you think!
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