Preparing Best-Ever Pork Tenderloin with Creamy Dijon Sauce is straightforward. Just follow these step-by-step instructions:

1. Preheat the Oven: Start by preheating your oven to 400°F (200°C).
2. Prepare the Pork: Pat the pork tenderloin dry with paper towels. Season it generously with salt and pepper on all sides.
3. Sear the Pork: In an oven-proof skillet, heat the olive oil over medium-high heat. Once hot, sear the pork tenderloin for about 3-4 minutes on each side until golden brown.
4. Transfer to Oven: Once seared, transfer the skillet to the preheated oven. Cook for 15-20 minutes or until the internal temperature reaches 145°F (63°C).
5. Rest the Pork: Remove the skillet from the oven and transfer the pork to a plate. Allow it to rest for about 5-10 minutes.
6. Make the Sauce: In the same skillet, lower the heat to medium. Add the minced garlic and sauté for about 30 seconds until fragrant.
7. Add Cream and Mustard: Slowly whisk in the heavy cream, Dijon mustard, and whole grain mustard if using. Continue to whisk until the sauce is smooth and thickened slightly.
8. Final Seasoning: Stir in the fresh thyme and season the sauce with salt and pepper to taste.
9. Slice the Pork: Slice the resting pork tenderloin into medallions, about ½ inch thick.
10. Combine: Pour the creamy Dijon sauce over the sliced pork, or serve it on the side.

Following these steps will lead you to perfectly cooked pork tenderloin bathed in a luscious sauce that is bound to delight your family and guests alike.