In a medium bowl, combine 1 tablespoon of fish sauce, 1 tablespoon of the ginger, 2 teaspoons brown sugar, 1 teaspoon salt and ¼ teaspoon pepper.

Set aside. Place the sirloin tips between 2 sheets of plastic wrap and, using a meat mallet, gently pound them to an even ½-inch thickness. Add the beef to the fish sauce mixture and turn to coat. Marinate at room temperature for 15 minutes.

Bring a large pot of water to a boil. Add the noodles and immediately remove the pot from the heat.

Let the noodles stand, stirring 2 or 3 times, until tender, 3 to 5 minutes. Drain in a colander, rinse under cold water and drain again. Transfer to a large bowl and set aside.

In a small bowl, whisk together the remaining ¼ cup fish sauce, the remaining 1 tablespoon ginger, the remaining 3 tablespoons brown sugar, the lime juice, water and chili-garlic sauce until the sugar dissolves. Set aside.

In a 12-inch nonstick skillet over medium-high, heat the oil until just smoking. Add the beef and cook until well browned on both sides, turning once, about 6 minutes. Transfer to a plate and let rest for 5 minutes.

Meanwhile, to the noodles add ½ cup of the fish sauce–lime juice mixture, the mint, cilantro and peanuts; toss to combine. Transfer to a serving platter or individual bowls.

Cut each piece of meat into thirds with the grain, then slice as thinly as possible against the grain. Place the slices on top of the noodles and drizzle with the accumulated juices. Serve with the remaining fish sauce–lime juice mixture on the side.