Bring a saucepan three-fourths full of water to a rolling boil, then remove from heat. Drop the noodles into the water and stir well. Let the noodles stand until tender, about 30 minutes. Drain well.
In a small bowl, combine the fish sauce, lime juice, and sugar and stir with a fork to dissolve the sugar. Set aside.
Warm a wok or a large frying pan over high heat, then swirl in the canola oil. Add the shrimp, garlic, and pepper flakes and stir-fry until fragrant, about 1 minute. Pour in the eggs and let them cook, without stirring, until lightly set, about 30 seconds. Then, stir well to scramble the eggs with the shrimp. Add the fish sauce mixture and drained noodles and cook, lifting and stirring the noodles constantly, until the ingredients are well blended, about 2 minutes. Stir in 1 cup of the bean sprouts, 2 tablespoons of the nuts, and 2 tablespoons of the green onions, and cook, stirring, until heated through and evenly distributed, about 1 minute longer.
Transfer the noodles to a platter. Garnish with the cilantro, mint, remaining bean sprouts, peanuts, and green onions. Serve right away.