In a large bowl, whisk together the flour, polenta and salt. Add the eggs and whisk until smooth. Add the trout, corn, onion, lime zest and salt then stir until well combined. It should be a nice thick consistency.
Heat oil in a large frypan over medium heat. Working in batches, spoon ¼ cup of the batter per fritter into the pan. Cook until browned, about 3-5 minutes per side. Drain on paper towel.
Serve with a dollop of yogurt, a sprinkle of coriander and a squeeze of lime