Heat the oil in a heavy-based sauce pan or wok on a medium heat (Gas 3/electric 120). It is important not to fry these on too high a temperature or they risk breaking apart. To test if the oil is ready, drop in a tiny amount of the batter. If it bubbles and floats to the surface then the oil is ready.
Beat together the flour, egg, curry powder, chilli powder, milk, salt and pepper.
Mix in the sliced onions and continue to gently beat, making sure not to crush or mash the onion slices.
Next, take about a tablespoon of batter and press a cube of brie into the centre.
Using another spoon, scoop the batter off the first spoon straight into the oil. Repeat until all batter is used.
Fry until golden brown and crispy.
Drain on kitchen paper.
Season well and sprinkle with the chopped herbs.