Make the adobo rub by blending the first 6 ingredients in the bowl of a small food processor into a smooth puree, scraping the sides halfway through to incorporate fully. Alternatively, you can use a mortar and pestle or mash the mixture to a paste on a cutting board with the side of a knife.

Cut a series of deep holes throughout the tenderloin with a paring knife and rub it down with the adobo, pushing the seasoning into the holes. Let marinate for 30 minutes on the counter or up to overnight in the refrigerator. 

When you’re ready to roast, heat the oven to 400°F. Line a rimmed baking sheet with foil. Place the tenderloin in the center of the pan and place the pan on the center rack of the oven. Roast until the internal temperature is 145°F in the thickest part, about 25 – 30 minutes, flipping every 10 minutes to evenly brown the outside. (If your pork hasn’t browned by the time it hits 145°F inside, you can give it a quick blast under the broiler for more browning.)
Remove the pan from the oven and set the tenderloin on a carving board to rest for about 10 minutes.

Pour the remaining lemon juice into the baking pan and carefully mix it into the pork juices, scraping up any browned bits with a wooden spoon or spatula. Pour the pan juices into a small bowl and adjust the seasonings to taste.

Cut the pork into 1-inch slices and transfer to a serving dish. (It will taste best and won’t dry out if it’s still slightly pink inside, so if you see that, it’s a good thing!) Serve with the reserved pan juices.