In frying pan, heat a little oil over medium heat and add the tomato and green onion. Season with salt and pepper. Heat for around 3 minutes, until tomatoes are starting to break down. Add the shrimp and red pepper flakes. Mix well to coat in tomatoes, and cook for just a minute to warm through.
Heat a broiler-safe frying pan over medium heat. Add a little olive oil, and when hot, pour in half the beaten eggs, seasoning them well with salt and pepper first. Cook for 1-2 minutes until the underside of the egg is beginning to set but the top remains runny.
Sprinkle the oregano over the omelette, then pour half the tomato and shrimp mixture over the top, making sure the shrimp are in an even layer. Crumble over the feta cheese, season with salt and pepper, and add a drizzle of oil.
Place the omelette under the hot broiler, and broil for 3-4 minutes until the egg is just cooked through. Remove, serve, and enjoy.