Fill a bowl with water and lemon juice. Remove the dark red leaves from the banana flour and slice the remaining leaves thinly down until you reach a point just above the the long filament seeds encased within the flower. Place the sliced leaves in the lemon water for around 30 minutes.
In a large bowl combine the sprouts, prawns, mango, herbs, peanuts, sesame and chilli together. Drain and rinse the banana flower thoroughly before adding it to the other ingredients. Combine the fish sauce, maple syrup and lime juice and stir through the salad.
Note: Sour mango is available from Asian stores. If you can't find it use an unripe mango.