1. Add the fava beans to a small pan of boiling water. Cover and simmer gently for about 3 minutes, until the beans are just tender. Drain and cool under cold running water. Use your fingers to gently squeeze the green beans out of their grey outer casings. Set aside.
2. Heat the olive oil in a large pan and cook the onion and garlic over a low heat, stirring occasionally, until softened but not colored. Add the leeks and asparagus and cook gently for about 3 minutes, turning them occasionally.
3. Pour in the vegetable broth and turn up the heat. Add the peas and when the broth is nearly boiling, reduce it to a simmer and cook for 10 minutes. Add the fava beans, artichoke hearts and spinach or chard. Cook gently for 6–8 minutes, until all the vegetables are tender and retain their fresh green color. Season to taste with salt and pepper. Stir in the chopped mint and serve the vignole ladled into shallow bowls with a drizzle of olive oil. Scatter with shavings of Parmesan.