Preheat oven to 200 °C.
Peel and dice the peppers. Peel and dice the onion finely. Dice the courgettes.
Add a splash of olive oil to a frying pan and cook the onion with a pinch of salt. Once soft, add the peppers, cook for 5 minutes and then add courgettes. Cook for a further 3 minutes. Season with salt and pepper.
Beat the eggs vigorously, season with salt and piment d'Espelette. Pour eggs over the vegetables in the frying pan. Cook over a low heat for 2 minutes and place the pan in the oven and cook for 10 minutes.
Remove the frittata from the pan and allow to cool. Serve in wedges at room temperature with a fresh green salad.
«You can also add tomatoes or preserved artichokes.»