How to cook scallops that will prevent them from becoming too rubbery

I've had this issue with crappy supermarket scallops before. Alton Brown covered this. From http://www.goodeatsfanpage.com/Season9/scallops/scallop_trans.htm (section 5):

dry scallops are usually ivory, or slightly pink, or even orange in color, not white. Of course, they don't actually look dry. The term refers to the fact that these lovely lozenges have not been soaked in any kind of chemical, say, sodium tripolyphosphate. This solution is used to help scallops retain moisture when frozen. Now there's nothing wrong with that per se, unless the scallop in question is not going to be frozen. You see, treating fresh scallops with S.T.P. causes them to gain moisture, making them heavier, which could be a good thing for a retailer, but it's never good for a cook. Because once this stuff is inside the scallop, they become very difficult to cook properly, and they are impossible to sear properly.

Diver scallops are probably good. Look for a bit of color when buying. The good news is that you probably aren't doing anything wrong, the scallops just aren't going to sear.

When you buy for searing, get scallops that haven't been treated with chemicals. Diver scallops are almost always untreated. Look for a bit of color, which is usually a sign of quality. Don't buy them if they are in a pool of milky liquid (as they usually are in the fish section of the supermarket). Buying diver scallops is also much more sustainable and eco-friendly, since large ships that freeze their stock at sea dredge the floor to get scallops. Divers are much more selective and do negligible damage to the ocean floor.

Calamari or squid is of course famous for being difficult to cook, because it gets tough or rubbery.

As Harold McGee explains in On Food and Cooking, octopus and squid meat are very rich in collagen:

They are chewy when lightly cooked, tough when cooked to the denaturing temperatures of their collagen, around 120 - 130 F / 50 - 55 C, and become tender with long, slow cooking.

The trick then is to either:

• Cook them minimally, so they do not begin to toughen. This Serious Eats recipe for fried calamari recommends no more than one minute.

  My own interpretation of this is that it will keep the temperature of the squid below the 120 F threshold, at the risk of being below the pathogen kill point, so it should be done only with squid from a trustworthy purveyor.

• Cook them for a long time, slowly, as in a braise, so they move through the tough phase to tender again. This Food Network recipe for stuffed squid by Ann Burrell is an example. The total squid cooking time is 20 to 25 minutes.