Place the zucchini, flour, bicarb soda, Parmesan cheese, garlic powder, oregano, marjoram, basil, black pepper and sea salt into a large bowl then stir to thoroughly mix. In a separate bowl, beat the eggs with buttermilk then stir the egg mixture into the zucchini mixture to make a batter.
Heat the vegetable oil and olive oil in a frying pan over medium heat until hot then gently spoon about 1/4 cup of zucchini batter per fritter into the hot oil. Fry the fritters in batches until golden brown on both sides, about 3 minutes per side; drain on paper towels then set the fritters aside to keep warm.
To serve, place a slice of mozzarella cheese and a slice of tomato on top of each fritter then sprinkle with sea salt.