1. Cut the cold cooked potatoes into a medium dice.
2. Cut the pepper into a medium dice and a little into julienne for garnish.
3. Blanch the peas.
4. Pre-heat the grill to hot.
5. Break the eggs into a bowl, season to taste and beat.
6. Heat a frying pan over a medium heat and add the butter and oil.
7. When the butter begins to bubble add the potatoes, diced pepper and peas.
8. Gently stir-fry for a few minutes to allow them to heat through.
9. Add the beaten egg mixture to the pan. Move the pan with one hand and stir with a fork or spatula with the other until the omelette reaches the still runny on top stage (‘baveuse’).
10. Slide the pan under the grill for a few moments until the omelette turns a nice golden brown in color.
11. Remove from the grill and carefully slide the spanish omelette from the pan onto a warmed plate, keeping it flat.
12. Garnish the spanish omelette with a little julienne of pepper and a few chives and serve immediately.