Preheat your oven to 180°C (350°F). Grease a large baking dish with vegetable oil.
In a large bowl, combine the grated zucchini, grated carrot, chopped garlic, sliced red onion, and strips of both red and yellow bell peppers. Season with salt, paprika, and garlic powder, mixing well to ensure all vegetables are evenly coated.
In another bowl, whisk together the eggs, milk, and soy sauce. Gradually sift in the flour and baking powder, whisking continuously to avoid lumps. The batter should be smooth.
Pour the batter over the vegetable mixture, adding the grated cheese. Mix everything together until well combined.
Transfer the mixture to the prepared baking dish, spreading it out evenly.
Place in the preheated oven and bake for about 45-50 minutes, or until the top is golden brown and a toothpick inserted in the center comes out clean.
While the bake is cooking, mix together the ketchup and mayonnaise in a small bowl.
Once the bake is done, remove from the oven and let it cool slightly. Drizzle the ketchup and mayonnaise mixture over the top.
Garnish with chopped spring onions before serving.