Grate the large onion and zucchinis into a bowl. Add the mozzarella, cheddar, parmesan, eggs, black pepper and pink himalayan salt. (You can change the amounts of each cheese based on your preference and which one you may like more of than the other)
Heat the oil in a frying pan over medium-high heat. When the oil is at the point of reaching frying level, take spoonfuls of the batter and drop them into the oil. Cook until outside is golden and inside is cooked through, which should take about 1-2 minutes. Repeat until all batter has been fried.
Ideally should be served immediately and could add a sprinkle of parsley for presentation.