Cook the noodles according to packet instructions, drain well, rinse under cold running water, then set aside. Finely slice or tear the mushrooms, leaving any smaller ones whole. Peel the garlic and deseed the chilli, then finely slice. Peel the ginger and trim the courgettes, then slice both into matchsticks. Pick the coriander leaves and set aside, then finely slice the stalks. Trim and finely slice the spring onions, reserving the green part for later.
Heat a good lug of oil in a large wok over a high heat, then add the mushrooms and fry for 3 to 4 minutes, or until slightly softened. Add the chopped garlic, chilli, ginger, courgette, coriander stalks and the white part of the spring onions. Fry for a further 3 minutes, or until softened and lightly golden.
Meanwhile, combine the cornflour and 2 tablespoons of water, then mix in the soy, agave syrup, sesame oil and rice wine or sherry. Stir the mixture into the pan and cook for a further 3 minutes, or until thickened.
Roughly chop and add the spinach along with the noodles. Toss well to warm through, then tear in most of the coriander leaves. Serve with lime wedges, sambal or chilli sauce and the reserved coriander and spring onions scattered on top.