Boil a pot of salted water. Blanch the vegetables one by one keeping the same cooking water each time as follows: turnip greens 15 seconds, fennel 30 seconds, broccoli 30 seconds, green beans 30 seconds.
As soon as you have blanched a vegetable, remove it from the water and plunge it into very cold water to stop the cooking.
When you have all the vegetables ready and nice and drained, mix them and add plenty of freshly chopped mint, a little olive oil, salt and pepper. Serve at room temperature.