Unwrap the noodles and place them in a large bowl. Pour over 1 ltr cold water, adding a little more if the noodles aren't fully covered, and set aside to soak for 25 mins.
While the noodles soak, chop the smoked tofu into bite-size pieces. Peel the red onion and thinly slice it. Halve the red pepper and scoop out the white membrane and seeds. Slice the pepper into thin strips. Top and tail the courgette and slice it into 1cm rounds. Scrub the carrot and use a vegetable peeler to create ribbons, peeling down to the core then thinly slice the core. Peel and grate the garlic and ginger.
Pour 1 tbsp oil into a large frying pan or wok and warm over a high heat for 2 mins. Add the tofu and cook for 4-5 mins, turning every min or so, till golden brown on all sides. Use a slotted spoon to transfer the tofu to a plate and set aside.
Put the empty pan back onto a high heat and add the sliced onion, pepper and courgette with 2 tbsp water and stir fry for 2-3 mins, till slightly golden at the edges.
Stir the garlic, ginger and carrot ribbons into the pan. Sprinkle in 1 tbsp mild curry powder and add a pinch of salt and pepper. Stir and continue to cook for 1 min.
The noodles should be tender all the way through, so drain them and shake off any excess water. Tip into the pan along with the cooked tofu. Drizzle in 2 tbsp sweet chilli sauce. Toss everything together to combine, and cook for 2-4 mins, till warmed through.
Pile the noodles into a couple of warm bowls or plates. Slice the lemon into wedges and serve on the side for squeezing, along with any leftover sweet chilli sauce.