Every pig has two tenderloins that run under either side of the lower backbone. Each tenderloin has a blunt end tucked into the pelvis, a roughly cylindrical cross-section through most of its length, and then a tapered end at the forward end of the pig. (See this post on pork-cutting for more details and photos.)
As the name tells us, this cut is very tender. It is also very lean – almost perfectly lean – so it doesn’t have much distinct pork flavour.
There is a band of silverskin on the tenderloin which some chefs have told me contributes moisture and flavour to the meat. Occasionally I find myself chewing on this silverskin, so I prefer to remove it before cooking.
Tenderloins can be brined as described in this post. This will season the meat throughout its mass and increase its tenderness and moisture-holding capacity. If you forgo the brine, you should season the tenderloin about thirty minutes before you intend to cook it to let the salt penetrate the meat.
As with all lean, tender pork, tenderloin should be cooked medium-well (65°C or 150°F). Because of its slender proportions, I usually sear the tenderloin in a pan and then transfer to a gentle oven to bring to temperature. If put directly into an oven without searing tenderloin will most likely overcook by the time an appetizing colour develops. They also work well on the grill.
Below is a pork tenderloin with buttered vegetables and saffron cream.