In a medium skillet over medium heat, combine potatoes, onion, bell pepper, and olive oil. Sauté until onion begins to brown, then remove from heat and set aside.
In a large mixing bowl, combine the egg substitute or beaten egg, flour, and milk. Whisk until smooth. Add seltzer and stir just until blended.
Coat a 6-inch nonstick skillet with nonstick spray, and place over medium heat. Pour about 1/4 cup of the batter into the hot pan, swirling it to coat the bottom. When the edges of the batter look firm, in about 1 minute, slide a spatula under the crepe and flip it over. When the crepe is firm and golden, transfer to a platter. Repeat with remaining batter.
To assemble crepes and filling, put about 1/4 cup of filling in a line down the center of the crepe, then fold two opposite sides to overlap one another. Repeat with remaining crepes and filling.
Serve and enjoy!