Squeeze the juice from the lemon. Place the juice and all other marinade ingredients in a bowl and mix well.
Pour marinade over pork tenderloin and marinate in the refrigerator for 3-4 hours
When you're ready to cook, preheat the oven to 350 degrees
Heat a skillet over medium-high heat. Once hot, remove tenderloin from marinade and sear 2-3 minutes on each side. (Do not discard marinade)
Place tenderloin in baking dish, uncovered, in the oven and cook for 30-40 minutes. The internal temperature should be 145 degrees.
In the skillet where you browned the meat, add the chicken broth and 3 tbsp of marinade. (The rest of the marinade can now be discarded)
While it heats, use a spatula to scrape of any remaining browned pieces of meat from the skillet. Bring to a boil.
Boil for 3-4 minutes until reduced to a thicker sauce.
Remove from heat and add butter, and stir until melted and combined
Slice tenderloin against the grain and serve with sauce poured over it or on the side.