In a mixing bowl, combine the flour, water, salt, and garlic powder. Whisk until smooth and well combined.
Stir in the shredded mozzarella cheese, chopped green onions, and bell pepper if using. Mix until evenly distributed.
Heat a non-stick skillet over medium heat and add the vegetable oil, swirling to coat the bottom.
Pour about 1/2 cup of the batter into the skillet, spreading it into a circle about 1/2 inch thick.
Cook for 3-4 minutes until the bottom is golden brown, then flip and cook for another 3-4 minutes until the other side is golden and the cheese is melted.
Remove from the skillet and repeat with the remaining batter, adding more oil as needed.
Serve warm with dipping sauce or soy sauce on the side.