To make the dressing, combined the soy sauce, vinegar and white sugar in small bowl. Stir until sugar is dissolved. Add the garlic and Thai chile, stir until well combined.
Prepare quinoa as instructed on the package, let cool to room temperature.
In a large bowl, combine quinoa, red leaf lettuce (or Napa cabbage), carrots, mint, coriander, scallions and lemongrass. Add 2 tablespoons of the dressing and mix well. Taste and add more dressing as needed. I find that that 2 tablespoons is generally enough.
Notes
1 Thai chile with membrane and seeds will make the dressing quite spicy. For more spiciness use two Thai chiles. For less spicy dressing use one Thai chile, membrane and seeds removed.