Self-contained countertop roaster ovens make a useful complement to the oven in your range, consuming less energy and releasing less heat into your kitchen. They're not a perfect replacement -- getting crisp skin on a turkey requires some ingenuity -- but they are highly useful nonetheless. For example, you can use your roaster oven as an extra-large slow cooker for occasions when you're preparing jumbo batches of your favorite stew or braising a large cut of meat.
Peel, chop, blanch and season your ingredients as you would for any slow-cooker recipe. Meat-based recipes typically call for browning the meat first, an optional step but one that adds rich, savory flavors to your finished dish.
Layer your meat, vegetables and aromatic ingredients such as onions and garlic in the roaster's insert. Vegetables take the longest to cook, so they should go in first. Arrange them with dense, slow-cooking vegetables such as carrots on the bottom and quicker-cooking potatoes or squash above, or add the quicker-cooking vegetables later in the cooking process. Meat goes on top so the juices and drippings can flavor the vegetables.
Pour in enough liquid to cover the bottom of your roaster insert to a depth of ½ inch, if you're slow-cooking a roast or other relatively tender cut. If you're braising a tough cut such as shank or brisket, add enough liquid to immerse the meat at least halfway. Broth, water, wine and thinned sauces or gravies all provide suitable cooking liquids.
Season the ingredients and cooking liquid with salt and pepper or other spices, as desired. Cover the cooker with its lid, and set your cooking time and temperature. If your recipe called for a slow-cooker's Low setting, turn the roaster to 200 F. To simulate the High setting, turn the roaster to 250 F.
Slow-cook your food as directed in your recipe, usually 4 to 6 hours at 250 F or 8 to 10 at 200 F. To convert a recipe from roasting to slow-cooking, allow about three times the recommended roasting time. Don't check your food until near the end of your expected cooking time, because this allows much of your heat to escape and can extend your cooking time unnecessarily.
Remove the lid carefully at the end of your cooking time, taking care to avoid the hot steam that escapes. Remove the cooked food, if appropriate, and thicken the cooking liquid to make your sauce. If you've prepared a stew or casserole, it's not usually necessary to remove the solid food before your final thickening.