In a bowl, crack 4 eggs, add 1 teaspoon of salt, and whisk thoroughly.

Finely dice half a medium onion (about 1/2 cup), 1 tablespoon of green bell pepper, and 1 tablespoon of red bell pepper.

Add the diced vegetables and 1/4 teaspoon of ground black pepper to the egg mixture. Stir to combine.

Preheat a non-stick pan over medium-low heat. Add a drop of vegetable oil and brush to coat the surface.

Pour a portion of the egg mixture into the pan. Once it's mostly set, carefully roll it up from one side.

Push the roll to one side, oil the pan, and pour more egg mixture, connecting it to the existing roll. Repeat until all the egg mixture is used, rolling it up layer by layer.

Use the spatula and the sides of the pan to press the omelette into a rectangular shape. Cook on all sides for a minute until firm.

Transfer the cooked omelette to a cutting board and let it cool for a few minutes. Slice into 1-inch thick pieces.

Arrange the Gyeran-mari slices on a plate and enjoy!