If the fava beans are young and tender, there is no need to peel them. If not, blanch the beans in a medium pot of boiling salted water for 30 seconds, just to loosen the skins. Drain, transfer to an ice bath to cool, and drain again. To peel the favas, pinch open the skin at one end of each bean and squeeze out the bean.
Toss the fava beans with the vinaigrette in a medium bowl and season with salt. Grate the ricotta over the favas, sprinkle pepper over the top, and serve immediately.
To make the lemon vinaigrette:
Whisk together the lemon juice, marmellata, and olive oil in a small bowl. (The vinaigrette can be refrigerated for up to 3 days.) Makes ¾ cup.