Add the grated zucchini, carrots, 1/2 cup corn kernels, chopped cilantro, salt and pepper to a large mixing bowl. Set aside.
Add the 1/2 cup chopped purple onions to a small frypan or skillet along with the 2 teaspoons of oil and one to two teaspoons of ground cumin. Stir over a medium heat until the onions have softened.
Add the onions to the veges in the mixing bowl and stir to mix thoroughly.
Using a smaller bowl- add the flour and the baking powder - aerate and mix using a whisk.
Stir the flour into the vegetable mixture.
Add two eggs and the milk to your now empty mixing bowl and whisk to combine.
Add the eggs to the vegetable mixture and mix thoroughly (If the mixture is too thick- add in some extra milk or if too thin-add in some extra flour. The consistency of fritters can vary a little just depending on the moisture content of the ingredients used).
Heat a large pan and add some extra oil for pan-frying the fritters. A medium high heat should be used.
Drop large spoonfuls of the mixture into the hot pan. Cook fritters a few minutes each side, until nicely golden and cooked through. You may need to cook in batches- place cooked fritters into a warmed oven, cover with foil.
While cooking the fritters you can put the salsa together- combine all salsa ingredients. Add salt and pepper to taste.
To serve- place two or three fritters into the centre of each plate, Spoon on some bottled salsa, top with your fresh salsa and a dob of sour cream.