Bring a large pot of water to boil. Add shelled beans and blanch 1 minute then remove to a bowl of ice water. When cool, pinch open pale green skins and pop out deep green inner fava beans (no peeling necessary if using edamame). Combine beans, cucumber, onion, dill, and pepper flakes in medium bowl.
Put lemon juice in another medium bowl and whisk in oil in a slow steady stream until incorporated. Whisk in salt and pepper. Pour half of dressing over bean mixture and half over watercress, tossing each to combine.
Divide watercress among salad plates. Top with bean mixture and use a vegetable peeler to shave wide strips of pecorino over each salad. Serve with torn chunks of Country Bread.
Tip: To save time peeling fresh fava beans, look for shelled and peeled frozen fava beans in Middle Eastern markets. They can be thawed and used as is in this salad.