Make the crepe batter: In a medium bowl, whisk the flour and salt. Add the eggs, milk, water, and 1 tablespoon oil. Whisk until smooth, then let the batter rest while you make the filling.
Make the filling: Heat 1 tablespoon oil in a large skillet over medium heat. Add the onion and cook until softened, about 5 minutes. Add the ground beef and cook, breaking it into small crumbles, until no pink remains. Drain excess fat if needed.
Stir the garlic, sweet paprika, tomato paste, broth, salt, and pepper into the beef. Simmer until most of the liquid has evaporated and the filling is moist but not wet, about 5 minutes. Remove from the heat.
Cook the crepes: Lightly oil a nonstick 8- or 10-inch skillet and heat it over medium heat. Pour in about 1/4 cup (60 ml) batter, immediately swirling the skillet to make a thin round. Cook until the top looks dry and the bottom is lightly golden, about 1 minute. Flip and cook for about 20 seconds. Transfer to a plate and repeat to make 8 crepes, lightly oiling the pan as needed.
Heat the oven to 375°F (190°C). Lightly grease a 9-by-13-inch baking dish.
Make the sauce: Melt the butter in a saucepan over medium heat. Whisk in the flour and cook for 1 minute. Gradually whisk in the broth and paprika. Simmer, whisking, until lightly thickened, about 3 minutes. Remove from the heat. Whisk a few spoonfuls of the warm sauce into the sour cream, then stir the warmed sour cream mixture back into the saucepan. Do not boil the sauce after adding sour cream.
Fill the crepes: Spoon about 1/3 cup of beef filling down the center of each crepe. Fold the sides over the filling, then roll each crepe into a neat parcel. Place seam-side down in the baking dish.
Spoon the sour cream sauce over the filled crepes. Bake until hot and lightly bubbling around the edges, 15 to 18 minutes. Sprinkle with parsley, if using, and serve warm.