You've likely heard that calamari needs to be cooked for a minute--or for a very long time. Here's why: When you cook squid rapidly (just to heat it through), you're not doing much to transform the collagen from its tender native state. If you cook it just a moment too long, the collagen starts to denature, strands unravel, and you get rubber bands. At this point, you must shift to a longer cooking mode. Add some acid from tomatoes, and a long, low and slow braise, and you get hydrolyzed, tender collagen. And that's delicious.