Aromatic star anise, fish sauce, and a Thai chile infuse the broth with an intense flavor. When you slice the pork, hold the knife at a slant and cut the pork diagonally into very thin pieces—the meat will be more tender and will cook more quickly.
Place noodles in a large bowl. Add boiling water to cover; let stand 20 minutes. Drain.
. While noodles soak, cut tenderloin in half lengthwise. Cut each strip into thin slices. Heat 2 teaspoons oil in a Dutch oven over medium-high heat. Add pork, red pepper, and garlic; sauté 3 to 4 minutes on each side or until pork is lightly browned. Remove pork mixture from pan, and set aside.
. Heat remaining 1 teaspoon oil in pan over medium-high heat. Add ginger and onion; sauté 3 minutes or until onion is tender. Add broth and next 5 ingredients; bring to a boil. Reduce heat, and simmer, uncovered, 15 minutes or until liquid is reduced by one-third to about 3 3/4 cups. Strain broth through a metal sieve into a large bowl; discard solids. Keep broth warm.
. Divide bean sprouts among bowls; top with noodles. Place pork evenly over noodles. Ladle broth over pork; top evenly with basil. Squeeze 1 lime wedge over each serving. Serve with remaining lime wedges.