Prepare your spinach by removing any large stems. Finely chop the spinach leaves. Wash well and drain but do not dry your spinach.
In a medium sized frying pan heat 1 tablespoon of olive oil and saute the chopped green onions. After a minute or two, add the spinach to the pan. Cook, stirring regularly, for approximately 5 minutes until your spinach has wilted and cooked.
Transfer the spinach mixture to a fine sieve and drain well. You can use the back of a spoon to press down on the spinach to help squeeze out the liquid. After the spinach has cooled you can also use your hands or a cheesecloth to remove more of the liquid.
In a bowl combine the spinach, feta, sun-dried tomatoes, capers, 1 teaspoon salt, 1/2 teaspoon pepper and the egg. Mix well until all is combined.
Place your pork fillets on a flat surface. Place 1 - 2 tablespoons of the spinach filling at one end of each pork fillet and then carefully roll it up. Use your kitchen string or toothpicks to secure the rolls. Season your pork with salt and pepper to taste.
Preheat your oven to 350 degrees Fahrenheit.
Heat 2 tablespoons of olive oil in a frying pan and add the pork roll-ups. Fry them for a few minutes per side, until gold brown.
Transfer the roll ups to a parchment paper lined baking tray and bake, in the center rack of your oven, for 7 - 10 minutes, until cooked through.
Remove from oven and cut away the kitchen string or remove toothpicks before serving.