For the salsa, place all of the salsa ingredients together into a bowl and mix well to combine. Set aside.
For the guacamole, place all of the guacamole ingredients together into a food processor and blend until smooth.
For the tacos, slice the fish fillets into strips 1cm/½in wide and season with salt and freshly ground black pepper. (You can use the rest of the fish for making fish stock, or for another recipe.)
Place the flour, eggs, water and a pinch of salt into a food processor and blend until smooth.
Heat a deep-fat fryer to 190C/375F. Alternatively, half-fill a deep, thick-based pan with the sunflower oil and heat until a cube of bread dropped in sizzles and turns golden in 30 seconds. (CAUTION: hot oil can be dangerous. Do not leave unattended.)
Dip the strips of fish into the batter, then fry in batches in the oil for 3-4 minutes, or until golden-brown and crisp. Remove with a slotted spoon and drain on kitchen paper.
To serve, lay the tortilla wraps down flat on a plate or flat surface and place some lettuce leaves down the centre of each wrap. Arrange the fried fish over the lettuce, then spoon over some salsa and soured cream. Fold in the sides, roll up as tightly as you can and serve each taco with a dollop of guacamole.