Step 1: Preheat your oven to 400°F (200°C). Pat the pork tenderloin completely dry with paper towels. Season generously with salt and pepper.
Step 2: In a small bowl, combine the minced garlic, rosemary, and thyme. Spread the Dijon mustard evenly over all sides of the pork tenderloin. Then, press the herb mixture onto the mustard-coated tenderloin, ensuring a thick, even crust.
Step 3: Heat 1 tablespoon of olive oil in a heavy-bottomed, oven-safe skillet (cast iron is ideal) over medium-high heat until shimmering.
Step 4: Carefully place the crusted pork tenderloin in the hot skillet. Sear for 2-3 minutes per side, until a golden-brown crust forms all around.
Step 5: Transfer the skillet to the preheated oven. Roast for 15-20 minutes, or until an instant-read thermometer inserted into the thickest part of the tenderloin registers 145°F (63°C).
Step 6: Remove the skillet from the oven and transfer the pork tenderloin to a cutting board. Tent loosely with foil and let it rest for at least 5-10 minutes. This is crucial for juicy pork.
Step 7: While the pork rests, prepare the pan sauce. Return the skillet to the stovetop over medium heat. Add a splash more olive oil if needed, then add the minced shallot. Cook until softened, about 2-3 minutes.
Step 8: Deglaze the pan by pouring in the chicken broth and white wine (if using), scraping up any browned bits from the bottom of the pan with a wooden spoon. Bring to a simmer.
Step 9: Stir in the heavy cream and continue to simmer gently for 2-3 minutes, until the sauce slightly thickens. Stir in the chopped fresh parsley. Taste and adjust seasoning with salt and pepper as needed.
Step 10: Slice the rested pork tenderloin into thick medallions. Arrange them on a platter or individual plates and spoon the warm pan sauce generously over the top. Serve immediately and enjoy!