In a bowl, gently whisk the eggs with salt and oregano. Stir in the peas.
Finely chop the spring onions and halve the cherry tomatoes.
Heat the olive oil in a non-stick frying pan over medium heat. Add the spring onions and cherry tomatoes and sauté for 2–3 minutes, until softened.
Pour in the egg mixture, then scatter the olives and crumble the feta evenly over the top.
Cover with a lid, reduce the heat, and cook for 5–8 minutes until the omelette is set and the top is firm.
Sprinkle fresh mint leaves over the omelette, then slice and serve immediately.