1. Preheat your oven to 375°F. Pat the pork tenderloins dry with paper towels, then season them generously with salt, pepper, oregano, thyme, and onion powder.

2. In a small bowl, combine 1 tablespoon of olive oil with 1 tablespoon of Dijon mustard. Brush this mixture over the seasoned pork tenderloins.

3. Heat the remaining 1 tablespoon of olive oil in a large oven-safe skillet over medium-high heat. Sear the pork on all sides until a golden-brown crust forms, about 2-3 minutes per side.

4. Transfer the skillet to the preheated oven and roast the pork for 18-25 minutes, or until the internal temperature reaches 145°F. Remove the pork from the oven, transfer it to a cutting board, and tent it with foil for 5-10 minutes.

5. While the pork is resting, prepare the Dijon cream sauce. In the same skillet used for searing the pork, melt the butter over medium heat. Add the minced garlic and sauté for 1 minute until fragrant.

6. Stir in the lemon juice, heavy cream, Dijon mustard, and whole grain mustard (if using). Bring the sauce to a gentle simmer and let it cook for 2-3 minutes until slightly thickened.

7. Season the sauce with dried thyme, salt, and pepper to taste. If the sauce is too thick, thin it out with a tablespoon of water.

8. Slice the rested pork tenderloin into 1-inch thick pieces and arrange them on a serving platter. Generously spoon the Dijon mustard cream sauce over the top of the pork.