In a large bowl, whisk together the flour, granulated sugar, baking powder, baking soda, and salt until well combined.

In another bowl, mix the milk, melted butter, egg, and vanilla extract until smooth.

Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.

Heat oil in a deep fryer or large pot to 350°F.

Using a spoon or a piping bag, drop about 2 tablespoons of batter into the hot oil, frying a few donuts at a time until golden brown, about 2-3 minutes per side. Remove and drain on paper towels.

In a medium bowl, beat the softened cream cheese and powdered sugar until smooth. Stir in the diced strawberries and lemon juice.

Once the donuts are cool, use a piping bag or a small knife to create a hole in each donut and fill with the strawberry cheesecake mixture.

Dust the filled donuts with powdered sugar before serving.