Soak bean-thread noodles in very hot water for 15 minutes, then drain.

Reserve half of the noodles for another use.

Cut the remaining noodles into 3- to 4-inch lengths and toss with rice vinegar and salt.

Cut out and discard ribs from lettuce leaves, halving each leaf.

Soak 2 rounds of rice paper in hot water until pliable (45 seconds to 1 minute).

Spread one soaked round on a paper towel and blot with paper towels, leaving the remaining round in water.

Arrange a lettuce leaf on the bottom half of the sheet, leaving a 1-inch border.

Top with one-fourth of the peanuts and one-fourth of the noodles, arranged in a line across the lettuce.

Top with one-fourth each of scallion, carrot, cabbage, and herbs.

Roll up tightly, folding insides after the first roll to enclose the filling.

Spread the remaining soaked rice paper round on a paper towel and blot.

Wrap around the spring roll.

Wrap the spring roll in a rinsed and squeezed paper towel and put in a resealable plastic bag.

Repeat to make 3 more rolls.

Chill the rolls, wrapped in wet paper towels in a sealed plastic bag, for up to 1 day.

Bring to room temperature before serving.

Discard paper towels.

Halve rolls diagonally and serve with peanut sauce.