For the Blueberry Filling:

1. In a small saucepan, add the blueberries, sugar, 3 tablespoons of water, and lemon juice.
2. Cook over medium heat until the blueberries burst and the mixture thickens, about 3-4 minutes after boiling.
3. In a small bowl, combine the remaining water with cornstarch and add to the blueberry mixture.
4. Stir until thickened, then remove from heat and let the mixture cool.

For the Cream Cheese Filling:

1. In a medium bowl, use an electric mixer to beat the cream cheese until light and fluffy, about 2-3 minutes.
2. Add sugar, lemon juice, and vanilla extract. Beat for another 2 minutes until well combined.

Assembling the Egg Rolls:

1. Place a couple of tablespoons of the cream cheese mixture in the center of each egg roll wrapper.
2. Add a spoonful or two of the blueberry filling on top of the cream cheese.
3. Dip your fingers in water and moisten the edges of the wrapper, folding in the sides and rolling tightly to seal.

Frying the Egg Rolls:

1. Heat oil in a skillet or deep fryer to 375°F.
2. Fry the egg rolls a few at a time for about 2-3 minutes on each side, or until golden brown.
3. Transfer to a paper towel-lined plate to cool. Dust with powdered sugar before serving.