Preheat the oven to 180°C/350°F/gas 4. Place the fish fillets in a large ovenproof dish and fill the dish with water. Cover the dish with foil and bake the fish for 20 minutes or until cooked through. Remove the cooked fish to a plate and set aside to cool for 10 minutes.
Use a fork to gently flake the cooked fish into a large bowl. Add the yoghurt, dill, lime juice and Tabasco and mash well.
Arrange the chopped avocado in a neat layer on each serving plate. Top with the Fish Mishmash and serve.