If you bought the fava beans still in the pod, remove them from the pod. The beans will still have a skin on them which you need to remove by cooking them in boiling water.
Bring a pot of water to a boil and cook the beans for 5 minutes. Using a slotted spoon, transfer the beans to a bowl. Once they are cool enough to handle, peel off the skins and discard. Place the peeled beans, garlic clove, mint leaves and lemon juice in a small food processor. You can also use a hand blender. Blitz and slowly add the olive oil until you have a smooth mixture. Transfer to a serving bowl. Cover and chill for at least one hour.
When ready to serve, drizzle with olive oil and sprinkle with the fresh parsley. I like to serve this dip with radishes but any crudite will work. Toasted pita is also nice.
Just a heads up that using fresh fava beans can take some time (removing from the pod and then peeling each bean). If you are short on time, you may want to see if you can find some fresh ones that are already out of the pod or are already peeled.