To prepare the fava bean dip to serve with crostini start bringing a pan of water to a boil, add the fava beans and cook for 4-5 minutes until tender. Drain and rinse under cold water, then shell the beans, discarding the skins.
Put the fava beans into a bowl and crush with a potato masher until mashed, but still retaining some texture. Stir in the lemon juice, olive oil, mint and salt and pepper to taste.
Heat the grill.
Toast the baguette slices on both sides. Cut the clove of garlic in half and rub the cut surface over one side of each piece of toast.
Spoon the fava bean dip on top of crostini: the recipe can be enjoyed paired with a slice of serrano ham.