Place the vermicelli in a bowl and cover with boiling water. Once softened and puffed, drain and roughly chop with kitchen scissors.
Whisk the fish sauce, lime juice, and crushed garlic together for a smooth dressing.
In a large bowl, combine the noodles with dry-roasted and coarsely crushed peanuts, onions, coriander, peppers, and prawns. Drizzle with the dressing, toss gently, and serve immediately.

Source: Thai Cooking for Beginners, Marabout.