Trim the end of the lemongrass stem, cut off the dry woody section at the top, then peel off 2-3 tough outer layers. Finely chop the pale, tender part of the stem. Thinly slice the cabbage with a sharp knife or mandoline. Shred the carrots using a julienne peeler or coarsely grate with a box grater. Thinly slice the apple.
Step 2 — Make sriracha lime sauce
Finely grate the zest of half the lime, then juice the lime. Combine the sriracha sauce (sriracha is a hot chilli sauce; if you prefer less heat, reduce to taste), 2 tsp lime juice and 2 tsp honey in a bowl and season with salt and pepper. Preheat the air fryer to 200C (see cooking tip). Bring a medium saucepan of water to the boil for the noodles.
Step 3 — Air-fry tofu
Put the cornflour in a large bowl. Cut the tofu into 2cm cubes. Dust the tofu with the cornflour and shake off the excess. Generously spray the tofu with oil and put in the air-fryer basket. Air-fry the tofu, shaking the basket halfway, for 10-12 mins until golden and crisp. Drizzle the sriracha lime sauce over the tofu. Air-fry for a further 1-2 mins until caramelised.
Step 4 — Cook noodles
Meanwhile, cook the noodles in the pan of boiling water for 7-8 mins until tender. Drain, then rinse under cold water to prevent the noodles from sticking.
Step 5 — Toss noodle salad
Combine the lime zest, half the lemongrass*, 2 tsp lime juice, 1 tbs olive oil and 2 tsp soy sauce in a large bowl. Add the noodles, cabbage, carrot and apple and toss to combine. Taste, then season with salt and pepper.
Step 6 — Get ready to serve
Pick the mint leaves, discarding the stems. Divide the noodle salad and tofu among bowls. Scatter with the mint leaves to serve.