Heat deep frying oil up to 170c, set up a frying station with draining paper and a slotted spoon.
Shred or slice finely both cabbages and place in a bowl, dress with a little olive oil and lemon juice and mix to make a slaw, set aside,
Finely chop jalapenos and the stalks of the fresh coriander (keep the leaves for garnish later) add both to the mayonnaise, season and mix thoroughly,
Make tempura batter by adding cold soda water to the tempura flour, whisking until smooth, keep as cold as possible, add ice if necessary.
Slice fish into little finger shaped pieces.
Dunk fish into batter and then place carefully into the frying oil,
Cook for 2 minutes each piece, it is done when the batter is crisp to the touch, be very careful when touching.
Place fish on the draining paper
Microwave the tortillas for 30 seconds, place 1 tbspn of the jalapeno mayo down the centre of the shell in a line.
Add mixed slaw and place 1 to 2 pieces of the fish on top
Garnish with fresh coriander