In a mixing bowl, crack 3 large eggs, then add a teaspoon of mirin, salt, and black pepper. Whisk vigorously for about 1 minute until the mixture is well blended and frothy.

Place a nonstick skillet over medium heat and add 1 teaspoon of vegetable oil. Let the oil heat for approximately 1 minute until it shimmers.

Once the oil is hot, add 1/4 thinly sliced zucchini and 1/2 scallion cut into 1.5-inch batons. Sauté for about 2 minutes until slightly softened, then add in 2 tablespoons of chopped kimchi and stir-fry for another minute.

Slowly pour the beaten egg mixture over the sautéed vegetables in the skillet. Tilt the skillet to ensure the eggs cover the surface. Reduce heat to low and cover with a lid. Cook for 2 minutes.

After 2 minutes, use a spatula to fold the omelet in half, encasing the filling. Cook for an additional 1-2 minutes until golden brown on the outside and soft inside.

Slide the Kimchi Omelet onto a plate. Serve hot, optionally with extra kimchi.