In a medium skillet cook leeks in the 1 tablespoon olive oil until tender; remove from heat.

In a blender container or food processor bowl combine parsley, thyme, Parmesan or Romano cheese, salt, and pepper. Cover and blend or process with several on-off turns until finely chopped. With the machine running, gradually add the 3 tablespoons oil; blend or process to the consistency of soft butter. Add leeks and nuts; process with several off-on turns until coarsely chopped. Set aside.

Remove fat and paper-thin membrane from surface of tenderloins. Use a sharp knife to cut each tenderloin lengthwise to, but not through, opposite side. Cover one tenderloin with clear plastic wrap. Using the flat side of a meat mallet and working from center to edges, pound the tenderloin to a 12x8-inch rectangle. Remove wrap; repeat with the remaining tenderloin.

Sprinkle tenderloins lightly with additional salt and pepper. Spread half the parsley mixture evenly over each tenderloin to within 1 inch of edges. Roll up each tenderloin from a short side. Tie rolls with string, if necessary. Insert a meat thermometer in center of one tenderloin. Place meat, seam side down, on a rack in a shallow roasting pan.

Roast, uncovered, in a 325 degree F oven for 45 to 60 minutes or until thermometer registers 160 degrees F. Cool about 30 minutes at room temperature. Remove string; cut into slices about 1/2 inch thick. Cover and chill.

Meanwhile, for Roasted-Garlic Mayonnaise, peel away outer skin from garlic. Cut off the pointed top portion with a knife, leaving the bulb intact but exposing the individual cloves. Place in a small baking dish; drizzle with 2 teaspoons olive oil. Cover and bake in a 325 degree F oven for 45 to 60 minutes or until cloves are very soft. Cool slightly. Press to remove garlic "paste" from individual cloves. Mash garlic with tines of a fork. Stir together garlic paste and mayonnaise or salad dressing. Thin mixture with a little milk, if necessary. Cover and chill in refrigerator at least 3 hours. Serve with Pork Slices. Makes about 32 slices.

Prepare pork and mayonnaise mixture. Cover and chill in the refrigerator up to 8 hours.