Cook crumbed fish fillets in the oven according to the instructions on the packet. Remove when done and allow to cool. Chop roughly into bite-sized pieces. Set aside.
Remove the husks on the corn. Place on an open flame or top shelf of grill/oven. Roast turning it occasionally, until evenly cooked on all sides and starting to char. Using a sharp knife or corn peeler, remove the kernels in a bowl.
To make the ceviche salsa place lemon juice, lime juice, sugar, salt, garlic, ginger, coriander roots and stem in a small food processor and blend until the consistency of a coarse pesto. Tip into a medium-sized bowl. Add the tomato, cucumber, onion, capsicum, paprika and cumin. Mix well. Adjust seasoning.
To assemble the tacos, place the tortilla on a plate. Spread some mashed avocado on the tortilla. Heap with baked crumbed fish pieces. Scatter the salsa on top of the fish. Garnish with coriander and jalapenos. Serve with lime wedges and sour cream.