for the pork: Place pork tenderloin in freezer to chill for 30 minutes. Remove from freezer and cut crosswise into very thin slices, about 1/8" thick. Then cut each slice in half lengthwise. Place pork pieces in a wide shallow bowl or large zip-top baggie.

In a small bowl, stir together sugar, fish sauce, 1 tablespoon of the sesame oil, soy sauce, black pepper, salt, and garlic. Pour mixture over pork pieces and fold several times to ensure the marinade is thoroughly mixed in with the pork. Cover bowl and place in refrigerator to marinate for 1 hour. Meanwhile, prepare the sauce and noodles.

for the sauce: In a small saucepan over medium to medium-high heat, stir together all sauce ingredients. Once sugar and salt have dissolved, remove from heat to cool to room temperature.

for the noodle salad: Bring a large saucepan of water to a boil. Add rice noodles, stir, and turn off heat. Let noodles soften according to the package directions, then drain and rinse in cold water in a colander. Shake very well to remove water and leave sit in colander at room temperature.

Divide noodles amongst four low wide bowls or plates. Top each with lettuce, carrots, cucumber, bean sprouts, cilantro, mint, and lime.

Remove pork from refrigerator. Heat a large cast iron skillet over medium-high to high heat. When hot, add remaining 2 tablespoons of the sesame oil and swirl around the bottom of the skillet. When oil is shimmering, carefully add pork. Separate pork pieces to cover bottom of skillet. Let pork sit without stirring for about 1 minute, to caramelize. Fold and repeat until pork is cooked through, about 5 minutes. Total cook time will depend on how thin the pork is cut, etc.

Divide hot pork amongst each of the four bowls. Serve with sauce to pour over individual bowls.