Preheat the barbecue or a griddle pan until hot. Oil and season the corn and grill until cooked and well charred all over, about 10 minutes. Slice the kernels off with a sharp knife.
Preheat the oven to 180˚C fan-forced or 200˚C conventional.
Gently fry the onion and garlic in a little oil until softened. Add the cumin, paprika and chill powder and cook for a further minute until fragrant. Take off the heat and add to a large bowl. Add the chicken, breadcrumbs, egg, chilli and chopped coriander, season and combine until evenly mixed.
Divide the mix into twelve even portions, moisten your hands with water and shape each portion into patties or football shapes.
Brown the koftas in a large frying pan with a little olive oil. Transfer to a lined baking tray and bake for 6-8 minutes until cooked through.
Smash the avocado flesh with a fork and pile onto your serving plate, season, squeeze over the lime and sprinkle on some Tabasco (if using). Place the koftas on top of the avocado, scatter over the extra coriander leaves and serve.