Place chillies in small heatproof bowl of boiling water; stand 15 minutes. Drain; chop chillies
Heat oil in small frying pan; cook onion and garlic, stirring, until onion softens. Stir in
chilli, oregano, paste and the water; bring to a boil. Remove from heat; blend or process, pulsing,
until mixture forms thick paste.
Place fish, in single layer, in large shallow dish; using fingers, pat chilli paste into both
sides of fish. Cover; refrigerate 30 minutes.
Meanwhile, make avocado cream - (Blend or process avocado and soured cream until smooth; stir in
coriander and juice.)
Cook corn on heated oiled grill plate (or grill or barbecue) until browned lightly and just
tender; slice thickly, cover to keep warm. Cook undrained fish on same heated oiled grill plate
until browned both sides and cooked as desired. Cover; stand 5 minutes. Slice fish thickly.
Meanwhile, heat tortillas according to manufacturer's instructions.
Divide fish, corn, avocado cream and tortillas among serving plates. Serve with lime wedges.