Preheat oven to 450F. Grease a cast-iron skillet with a bit of oil and set aside. (Alternately, you can use a rimmed baking sheet. Brush some oil on the baking sheet, as well).

Prepare the pork tenderloin by removing any visible fat and removing the silverskin. Brush pork with balsamic vinegar and season with salt and pepper. Place into a prepared pan or baking sheet, placing it along the side or at the end, if cooking potatoes alongside. Tuck the thin end of the tenderloin under, so that the pork is evenly thick from end to end.

(If cooking potatoes alongside, halve or cube the potatoes, toss with olive oil, salt and pepper. Place into the skillet or onto the baking sheet, cut side down.)

Place into preheat oven and roast for 25-30 minutes, or until the pork registers 145F when measured with an instant-read thermometer and the potatoes are golden.

Remove from oven. Remove the potatoes to a bowl and loosely cover with foil to keep warm. Remove the pork to a plate to rest while you make the sauce.

In the same skillet you used to cook the pork (or a fresh skillet if you cooked on a baking sheet), melt the butter over medium heat. Add the shallots or onion and cook, stirring until softened. Add the chicken broth, balsamic vinegar and fig jam. Increase the heat to medium high and cook, stirring, until sauce reduces and thickens. Taste and season with salt and pepper as needed. Add a few thyme leaves to the sauce, if using.

Return pork to the pan and re-warm, flipping it over a couple of times to coat with sauce. Remove pork to a plate and spoon warm sauce over-top or alternately, slice pork, then spoon sauce over-top. Serve with roasted potatoes.