1Pod the beans and blanch in boiling water for two minutes. Cool and squeeze the beans out of their skins. I don't bother to skin the smaller ones but it's important with the bigger beans.
2Mash half the beans, add the olive oil and mix to a paste.
3Gently heat 2/3rds of the butter in a separate pan, add the onions with a little salt and fry gently until tender. Add the garlic and cook for a couple more minutes.
4Heat the stock in another pan.
5Turn the heat up high and pour in the rice. Stir it with a wooden spoon until well mixed and coated. Add the vermouth and let it bubble fiercely for about a minute, stirring gently all the time.
6Turn the heat down and add a couple of ladles of stock, stir and keep stirring occasionally until the liquid has been absorbed. Repeat with two more ladles of stock and add the broad bean paste.
7Keep adding the stock, stirring frequently until the rice is al dente.
8Add the broad beans, parsley, mint and a little more stock and cook for a couple more minutes.
9Add the Parmesan and remaining butter. Stir in, check seasoning and serve immediately.