How to Make It
Soak 2 dozen 8-inch bamboo skewers in warm water for 30 minutes. Thread the steak onto the skewers and place on a large baking sheet.
In a food processor, combine the lemongrass, shallots, two-thirds of the garlic, 3 tablespoons of the sugar and the coriander and pepper. Pulse until a smooth paste forms. With the machine on, add 3 tablespoons of the fish sauce and 2 tablespoons of oil. Brush the beef with the marinade and let stand for 30 minutes.
Meanwhile, on a cutting board, use the side of a large knife to mash the remaining garlic and 3 tablespoons of sugar to a paste. In a small bowl, toss the garlic paste with the carrot slivers and let stand for 15 minutes. Stir in the remaining 5 tablespoons of fish sauce, the lemon juice, rice vinegar, water and one-third of the jalapeños.
In a large pot of boiling salted water, cook the rice noodles until just wilted, about 1 minute. Drain and rinse under cold water. Drain well, then transfer to a platter.
Light a grill. Lightly oil the grate. Grill the beef skewers over a medium-hot fire for 1 to 2 minutes per side for medium-rare meat. Arrange the skewers over the noodles and sprinkle with the peanuts. Serve with the dipping sauce, fresh herbs, bean sprouts, lettuce and the remaining two-thirds of the jalapeños so your guests can make their own bundles.