In a small saucepan, heat the soy sauce, mirin, lemon juice and sugar. Simmer for 5 mins until syrupy, then remove from the heat. Bring a large saucepan of salted water to the boil, then cook the noodles and broccoli for about 3 mins, adding the prawns a few secs before draining. Divide the mixture between 2 plates, pour the warm teriyaki sauce over the top, sprinkle with the red chilli and serve.
