Friend of The Food Geek, @DisneyDeborah, asks about slow cooking via Twitter, hoping for tricks, tips, resources, and the like.
There is a certain promise given by a slow cooker, and that is one of dumping a bunch of things into a pot, hitting a button, leaving it alone for 8-12 hours, and returning to fantastic food. It's a compelling vision, but ultimately more of a mirage than anything that can be truly achieved. There are some dishes that work well that way, but people try to push it too far, and it all goes wrong.
There are two essential parts to making the most out of your slow cooker. The first is to be prepared to do some extra work at the beginning to maximize flavor and keep everything from being just kind of blah. The second is to get to know what foods work best in a low-temperature, long-cooking, wet cooking methods.
One of the easiest things to make in the slow cooker is homemade stock. This requires minimal extra work, and you can use a wide variety of materials. Technically, this only make an ingredient which will go into a future dish, so it's not going to stand on its own. Stock is usable in so many dishes, especially future slow-cooker dishes. Plus, you can go from putting a tiny amount of effort to going mad with prep power in order to get all the flavor you can out of it.
The easiest way to make a great, say, chicken stock is to grab a bunch of legs and thighs, some carrots, celery and onions, dump it into the slow cooker, cover it with water, throw in some dried herbs and peppercorns, and cook it on low for 10-12 hours. Once it's done, ditch all of the solids and freeze the rest until you're ready to use it. Great in soups, braises, stews, pot pies, or whatever.
If you want to take it a step farther, chop the vegetables, put into a large pan with a little vegetable oil, add some salt, and cook over medium-low heat until the vegetables start turning translucent. Put all that in the slow cooker then do all the stuff from the previous paragraph.
Want to go just a step farther? Lightly coat the chicken legs and thighs with canola oil or similar, roast at 425°F until it browns a bit, then do all the stuff from the previous two paragraphs.
Want something without meat? Skip the chicken and add a bunch more vegetables. This is a good use for those vegetables that are looking a little sad but aren't yet decomposing.
There are two major reasons why you want to add extra steps to your slow-cooking. The first is that different foods cook at different rates, so if you try to cook the vegetables all the way through for the same time and temperature that you try to cook the meat, chances are good that your meat is going to overcook. Think about the difference between a carrot and a zucchini squash. A slice of carrot the same thickness as a slice of zucchini squash will be so much more dense and crisp than the squash. This will definitely affect cooking times, so you wouldn't want to add them at the same time. The carrot will have to cook for a longer time than the squash, all other things being equal.
The second reason you want to add separate steps is because there are temperatures at which extra flavors develop, and you aren't going to get those temperatures in the slow cooker. This is especially true with the browning that comes from Maillard reactions. The browning of toast, the sear of a steak, the browning of cheese in a baked macaroni and cheese casserole, and the crispy brown coating of a fried chicken are all that lovely dark temperature that comes from being heated to above the boiling point of water. There are a lot of flavors that happen in that browning, and you just can't get it from putting everything in a pot, covering it with water, and cooking for 4-12 hours.
To fix the problem of low temperature, if you're cooking some meat in a slow cooker, cut the meat to whatever size you plan to cook it at, and use high heat in a skillet, if it's small enough, or oven if it's too big, and cook the outside. The reason you want a high temperature is because you want to cook the outside quickly without cooking the interior much at all. If you were just cooking something on the stove or the oven, you'd likely use a lower temperature so that the outside is browned around the same time as the inside is fully cooked. However, since you will have several hours of cooking left, you want to pour as much heat in at once, get the outside cooked, and leave the inside as uncooked as possible.
Now that we've touched upon technique, let's look at ingredients. My other favorite no-fuss slow-cooker dish is to take the boston butt cut of a pig (a.k.a. the pork shoulder), put it in the slow cooker, cover with some beer, sprinkle some salt and maybe some spices, and cook over low heat for 10-12 hours. When you are done, the pork should fall off the bone and shred easily with a fork. It should, in fact, be quite difficult to keep together. You can use that in just about anything that works well with pork.
For those who don't eat pork, there are still good lessons to be learned. The shoulder is a hard working muscle, and traditionally is a lower-cost cut of meat. When you compare with, say, a filet mignon cut of beef, they are as different as can be. The filet is from a muscle that hardly gets any work at all. It's tender, needs to be cooked very little at high heat, and has not much flavor at all. The filet is a terrible cut to use in a slow cooker. What you want is the hard working muscles. These are filled with connective tissue that develops from all the work. There's lots of flavor in these cuts, but they have to be cooked very slowly, because the connective tissue won't dissolve until it hits a relatively high temperature for meat.
In order to keep from overcooking the outside of the meat before all of the connective tissue is dissolved, you have to cook it slowly. In order to cook it properly slowly, you want to use a wet cooking method. This all points straight to the slow cooker. So if you're cooking chicken, use the legs and the thighs, which work harder than the breast and other white meat portions. For beef, use the brisket. If it's a low-cost cut of meat compared to others cuts from the very same animal, then you're almost certainly using the right cut. If in doubt, ask your butcher what a good braising meat could be used.
So, now that you know the theory, let's get to the specifics. Fortunately, Fine Cooking has a slew of recipes for the slow cooker. Look for the ones that both sound great and use these principles in order to be sure that you're going to have the best slow cooking experience you can. Cut corners if you must, but when you're saving time from not doing the extra prep, be sure to use the best (and most appropriate) ingredients that you can find.