Mix all ingredients for the rub together in a small bowl and set aside.
Trim any loose parts off tenderloin and remove the silver skin.
Rub olive oil all over the tenderloins then apply the rub liberally on all sides. Allow the rubbed tenderloins to sit for 30 minutes.
Align both halves of the tenderloin so the thin end of one is matched with the thick end of the other.
Lay Meyer lemon slices on top of the paired tenderloin and tie them together with the butcher twine-make sure the lemon slices are under the twine.
Brush some olive oil on the lemon slices.
In a heavy bottom cast iron skillet, sear the tied pork tenderloin over medium high heat on all sides, starting with the lemon slices first.
Once seared, add about ½ cup of dry white wine to the pan then transfer the cast iron pan into the 425 degree oven and roast for about 30 minutes, until the internal temperature reads about 145-150 degrees on an instant read thermometer.
Remove from the oven and place the pork tenderloin on a cutting board to rest. Loosely tent aluminum foil over it and allow the pork to rest while you prepare the sauce.
If necessary, deglaze the cast iron pan with some water to remove any burned morsels on the bottom and wipe out with a paper towel.
Using the same cast iron skillet, melt 4 tablespoons of butter over a medium heat, then add the shallots and crushed garlic.
Saute until the shallots are starting to soften, about 3 to 4 minutes.
Add the flour and stir or whisk together until a light roux develops.
Add the lemon zest, lemon slices and some kosher salt and pepper. Let the lemon slices have direct contact with the bottom of the pan so they get a slight sear for a couple of minutes.
Add in the Worcestershire sauce, lemon juice, wine, stock and fresh rosemary and increase the heat until starting to simmer.
Stir well and bring to a simmer. Add the 2 remaining tablespoons of butter and shake the pan while that melts-simmer for about 5 to 10 minutes while the sauce thickens. Remove from the heat.
Snip off the butcher twine and slice the pork tenderloin on the bias. Remove the lemon peels and rosemary from the sauce and spoon over the sliced pork.