Combine the flour and baking powder in a mixing bowl and season with salt and pepper. Beat egg yolks with a small amount of the water in a small bowl (a 2 cup glass measuring pitcher works great for this). Whisk the egg mixture a little at a time into the flour and add additional water, as necessary, to achieve a smooth consistency for the batter.
Heat the canola oil in a deep-fryer to 375 degrees F or as instructed in the manufacturer's instructions for potatoes and fish or similar foods.
Fry potatoes in deep-fryer until golden brown and drain on paper towels. Season with salt.
Dip tilapia into batter, deep-fry until golden brown and transfer to paper towels to drain.
Serve with malt vinegar or your choice of condiments.