Using a spiraliser or Julienne peeler, cut the courgette into long thin pieces. Set aside.
Finely chop the garlic and spring onions.
Heat the oil in a frying pan then add the garlic and stir for a few seconds. Add the mushrooms, stir for 10 seconds then add the soy sauce, mirin, rice vinegar and lemon juice. Put a lid on, turn down the heat and gently sauté for about 8-10 minutes, until the mushrooms have softened.
Add the courgette, spring onions and sesame seeds. Add more soy and lemon juice if the pan is too dry. Stir-fry gently for about 3 minutes.
Stir in the sesame oil and coriander leaves, then serve.