Prepare the sauce first: Blend the corn flour and sugar in a small bowl with the lemon juice, stir in the remaining
ingredients and set aside.
Next prepare the Calamari, hold in one hand and gently pull the head with the other hand. The head and inside of the body will come away in a complete piece. Remove the bone found at the open end of the Calamari (it looks like a long piece of plastic). Clean under cold water and rub off the outer skin, then cut evenly into rings. Finely shred the ginger. Drop the Calamari into a saucepan of boiling water and cook for 10 seconds then remove immediately and drain.
Then cook: Heat the oil in a wok or large skillet and Stir fry the courgette for 2 minutes. Add the ginger, calamari and mushrooms and continue to stir fry for 2 minutes. Finally, add the sauce and cook, stirring constantly, until the mixture boils and thickens. Best served hot.