Prepare the Onions: Thinly slice 2 large onions.
Combine Dry Ingredients: In a mixing bowl, combine 1 cup all-purpose flour, 1 teaspoon baking powder, 1 teaspoon salt, and ½ teaspoon black pepper.
Add Wet Ingredients: Add ½ cup milk and 1 egg to the dry ingredients. Whisk until smooth.
Fold in Onions: Gently fold the sliced onions into the batter until they are well coated.
Heat the Oil: Pour vegetable oil into a frying pan, filling it about ¼ inch deep. Heat over medium heat until it reaches about 350°F.
Fry the Fritters: Using a spoon, drop spoonfuls of the onion mixture into the hot oil. Fry until golden brown on both sides, about 2-3 minutes per side. Flip them carefully with a spatula.
Drain the Fritters: Remove the fritters from the oil using a slotted spatula and place them on paper towels to drain any excess oil.