Pour boiling water over the noodles and let sit for 5 mins. Rinse under cold water and thoroughly drain before placing in serving bowl. Add the carrots, onion and half the herbs.
Meanwhile, make the dressing by mixing the lime juice, sugar and fish sauce, along with half the chillies.
Heat a non-stick frying pan or wok until extremely hot, then add a drizzle of oil. Cook the mince until it browns, breaking it up with the back of a wooden spoon and making sure it is cooked through. Tip over the noodle mixture, then toss over the dressing, giving everything a good mix. Serve in bowls, with the remaining herbs and chilli slices scattered on top.