Pork tenderloin, which comes from the loin portion of the hog, is a small, lean cut of meat. It cooks within minutes if you use a dry-heat method, such as roasting or pan-frying. Because it lacks the marbling found in fattier cuts of pork, such as Boston butt, it needs careful preparation to keep it from drying out. It also has a mild, almost bland, flavor, so marinades and seasonings are a must.

Slow cooker cooking is essentially braising -- a moist-heat method and you must include a liquid to keep the tenderloin moist and flavorful. Brown the tenderloin first in a skillet. Browning seals in juices and also adds flavor. Transfer the loin to the slow cooker and add a marinade. The marinade should only partially cover the meat. Cover and cook on low for four to six hours, or until the tenderloin is fork-tender. The USDA recommends a temperature of at least 145 degrees Fahrenheit for cooking pork safely. Allow the meat to rest for three minutes before you carve it.

Because pork tenderloin has such a mild flavor, you can pair it with almost any marinade or seasoning. Combine teriyaki sauce with vinegar, garlic, red pepper flakes and peanut butter to make a Thai marinade or whisk together apricot preserves and grainy mustard for a sweet and savory dish. You can even marinade pork tenderloin in nothing more than milk combined with savory herbs, such as thyme or rosemary. The milk tenderizes the pork and adds mild flavor. To marinate pork tenderloin, which the marinade ingredients together. Place the tenderloin in a baking dish or plastic bag and pour the marinade over the pork. Seal or cover and refrigerate at 40 F for up to five days. If you have room in your refrigerator, you can marinate the pork directly in the slow cooker insert. Don't worry about draining the marinade. Simply plug in the slow cooker and you're ready to go. Always cook used marinades to destroy bacteria.

Although you can cook a frozen pork tenderloin in the oven or skillet, meat should always be defrosted before cooking in a slow cooker. The slow cooker uses lower temperatures than the oven or skillet and frozen meat may not cook quickly enough to prevent bacterial growth. Be sure to use a slow cooker that's the right size for the meat. In general, the food should fill up about one-half to two-thirds of the slow cooker. A small or medium slow cooker works best for a tenderloin. You can also tie two tenderloins together for a large slow cooker. This method not only makes more servings, but can also keep the pork tenderloin moist.