Whisk together all ingredients for dressing.
Prepare an ice bath by filling a large bowl with ice and water.
Bring a large pot of water to a boil and salt it well. Blanch the snap peas (and/or any other tougher veggies you're not shredding) for a few minutes until crisp-tender then use a small colander, slotted spoon or tongs to remove them (keeping the boiling water) and plunge the veggies into an ice bath to cool quickly.
Add the rice noodles to the boiling water and cook according to package directions, or until just tender (about 5 minutes for the brand I use). Plunge them in the ice bath, too.
Drain noodles and vegetables by dumping them into a big colander and picking out and discarding any remaining ice cubes. Transfer to a large bowl and toss with herbs, shallot and dressing to coat. Top with peanuts. Serve chilled or room temperature.