Baja Fish Tacos

Steps

1. 1
   Squeeze the juice of one lime and cut the other into wedges.
2. 2
   For the salsa, mix the tomatoes, onion, jalapeño and half the coriander with a pinch of salt and half the lime juice. Set aside.
3. 3
   For the crema, whisk the soured cream and mayonnaise with the remaining lime juice and a pinch of salt until smooth, then chill it.
4. 4
   Cut the fish into 12 fingers about 2 cm thick, pat them dry and season with salt.
5. 5
   Heat the oil in a deep, heavy pan to 180°C/350°F; it should come no more than halfway up the sides.
6. 6
   Whisk 120 g of the flour with the baking powder, oregano and a pinch of salt, then whisk in the cold lager until just smooth and as thick as double cream. A few lumps are fine; overmixing makes the batter tough.
7. 7
   Dust the fish in the remaining flour, shake off the excess, dip it in the batter and lower it into the oil, 4 pieces at a time. Fry for 3–4 minutes, turning once, until deep golden and crisp, then drain on a rack.
8. 8
   Warm the tortillas in a dry frying pan for 30 seconds a side and keep them wrapped in a clean cloth.
9. 9
   Fill each tortilla with cabbage and a piece of fish, spoon over the crema and salsa, scatter with the remaining coriander and serve at once with the lime wedges.