Place the potatoes in a saucepan and cover with cold water. Place over high heat. Bring to a boil until tender. Drain well.
Heat a nonstick pan on medium heat. Warm the tortilla on both sides.
Warm the oil in a medium nonstick skillet over medium heat. Add diced potato and sauté for 3 minutes. Add tomatoes and sauté for 1 minute more.
Add the eggs to the pan. Cook eggs for 2 to 3 minutes until they just begin to set into large curds but are still moist, stirring gently and constantly until creamy but no longer runny. Season with salt and pepper to taste.
Stir in the cheese and chives. Spoon into tortillas and serve with orange juice.