Food Network teaches how to crush, slice and mince garlic. Peel off some of the papery skin from the garlic and then smash the head of garlic with the heel of your hand to loosen the cloves; if you only need a few cloves, leave the head intact and pull some off. Separate the cloves. To peel a clove, cut away the root end with your knife. Lay the flat side of the knife over the clove while holding the knife handle, then with the heel of your free hand carefully whack the knife against the garlic to separate the skin from the clove. To crush the peeled garlic, lay the flat side of the knife over the clove and smash it again. To slice peeled garlic, lay the clove flat on the cutting board and hold it with the fingertips of one hand, keeping them curled under. Using a rocking motion with the knife, make thin slices by moving the knife slowly across the clove. To mince peeled garlic, lay the flat side of a knife over the clove and smash it. Roughly chop the clove then move your free hand flat across the tip of the knife and use a rocking motion to chop the garlic until it’s finely minced.
Combine the lemon zest, lemon juice, 1/2 cup olive oil, garlic, rosemary, thyme, mustard, and 2 teaspoons salt in a sturdy 1-gallon resealable plastic bag. Add the pork tenderloins and turn to coat with the marinade. Squeeze out the air and seal the bag. Marinate the pork in the refrigerator for at least 3 hours but preferably overnight.
Preheat the oven to 400 degrees F.
Remove the tenderloins from the marinade and discard the marinade but leave the herbs that cling to the meat. Sprinkle the tenderloins generously with salt and pepper. Heat 3 tablespoons olive oil in a large oven-proof saute pan over medium-high heat. Sear the pork tenderloins on all sides until golden brown. Place the saute pan in the oven and roast the tenderloins for 10 to 15 minutes or until the meat registers 137 degrees F at the thickest part. Transfer the tenderloins to a platter and cover tightly with aluminum foil. Allow to rest for 10 minutes. Carve in 1/2-inch-thick diagonal slices. The thickest part of the tenderloin will be quite pink (it's just fine!) and the thinnest part will be well done. Season with salt and pepper and serve warm, or at room temperature with the juices that collect in the platter.