For the Marinated Pork: In a large zipper-lock bag, combine baking soda with ½ cup (120ml) water and swish until baking soda is dissolved. Add pork, press out air, and seal bag. Refrigerate for 15 minutes. Drain pork, rinse under cold running water, and pat dry. Rinse zipper-lock bag and reserve.

Meanwhile, if using a mortar and pestle, crush lemongrass, shallot, garlic, and palm sugar to form a rough paste. If using a food processor, combine lemongrass, shallot, garlic, and palm sugar and pulse, scraping down sides, to form a rough paste.

Transfer paste to a bowl and whisk in fish sauce, soy sauce, cornstarch, and vegetable oil. Add pork, tossing to coat. Transfer pork to reserved zipper-lock bag, press out air, and seal. Marinate at room temperature, turning pork once or twice, for 30 minutes. Alternatively, refrigerate up to 12 hours.

Meanwhile, light one chimney full of charcoal . When all charcoal is lit and covered with gray ash, pour out and arrange coals on one side of charcoal grate. Set cooking grate in place, cover grill, and allow to preheat for 5 minutes. Alternatively, set half the burners on a gas grill to the highest heat setting, cover, and preheat for 10 minutes. Clean and oil grilling grate.

Grill pork directly over high heat, turning frequently and shifting to cooler side of grill if there are excessive flare-ups, until pork is charred and just cooked through, 3 to 4 minutes total.

Fill serving bowls with chilled noodles, then top with pork, herbs, cucumber, pickled carrot and daikon, and peanuts. Drizzle everything with nuoc cham and serve with lime wedges.