To make the batter, soak both dais in a large bowl of water for 2 hours.
Drain the dais and transfer to a food processor or blender with the cumin and fennel seeds and dried chillies.
Season with salt.
Then process, gradually adding about 2-3 tablespoons water until it is a coarse, stiff batter.
Remove the outer layers of the plantain flower until you reach the finger-shaped white florets.
Remove the stamens from the florets and chop the florets finely.
Keep removing the inner layers and chopping the florets until you get 1 cup chopped flowers.
Put the yoghurt and water in a large bowl, add the chopped flowers and allow to soak until needed.
Heat the 3 teaspoons oil in a frying pan (skillet) over medium heat.
Add the mustard, cumin and fennel seeds and curry leaves and stir-fry for about 1 minute, or until the mustard seeds start spluttering.
Add the onion and stir-fry for about 1-2 minutes.
Drain the plantain flowers, squeeze out any excess water, add to the pan and fry for about 1-2 minutes.
Pour the contents of the pan into the batter and mix well.
Heat enough oil for deep-frying in a kadhai or deep frying pan to 180"C / 350’F, or until a cube of bread browns in 30 seconds.
Then reduce the heat slightly.
With damp hands, take a ladleful of the batter and flatten it into a 5cm / 2 inch round patty.
Working in batches, slip the patties gently into the hot oil.
Deep-fry, turning frequently, for 3-4 minutes, or until golden brown and crisp.
Remove with a slotted spoon and drain on kitchen paper (paper towels).