Place the vegetables in an airtight jar. Add the vinegar, sugar and salt, seal the jar, shake until the sugar and salt have dissolved. Leave the vegetables to stand at room temperature for at least 2 hrs. or overnight.
Heat the oil, sauté the ginger, garlic, lemongrass and lime zest. Add the mushrooms and cook for approx. 5 mins. Pour in the soy sauce and lime juice, bring to the boil, then simmer for approx. 2 mins. Place in a bowl and allow to cool slightly.
To fill the baguette
Spread one side of the baguette with mayonnaise, fill with the pickled vegetables, mushrooms and coriander.