In a saucepan, combine the dressing ingredients: broth, soy sauce, sugar, and tamarind or lemon juice. Bring to a boil and stir until sugar dissolves, about 2-3 minutes. To thicken, mix 1 tablespoon tapioca starch with cold water and stir into boiling mixture until glossy. Remove from heat and let cool.

Bring a pot of water to boil. Blanch chicken or beef for 5-7 minutes until fully cooked; let cool, then shred or slice thinly. For tofu, marinate for at least 15 minutes, then pan-fry in oil until golden, about 4-5 minutes per side.

Prepare rice noodles according to package instructions, usually boiling for 3-5 minutes until tender but firm. Drain, rinse under cold water, and toss with a drizzle of oil. Set aside.

Chop crisp lettuce, julienne carrots, and slice cucumbers. Finely chop herbs like cilantro, Thai basil, and mint. Keep ingredients separate until ready to mix.

In a large bowl, toss the chilled rice noodles with the cooled dressing until fully coated. Mix in your chosen protein, fresh vegetables, and herbs just before serving.