Immerse green beans in boiling water to blanch just until crisp tender.

Remove from water and immerse in an ice water bath to stop cooking process.

Just before serving, melt butter in a very large frying pan and fry the tender-cooked beans to get them hot again and just a bit crispy.

Sprinkle them with the parsley, orange zest, pistachios and salt and pepper to taste.

Serve immediately.