This wonderfully simple recipe comes from Anna Tasca Lanza of Regaleali Winery in Sicily.
Saute the onion & garlic in the olive oil in a medium saucepan until soft, about 5 minutes. Add the fava beans, half the parsley, and the water. Cover and cook until tender, about 10 minutes for fresh, young fava beans. Add salt to taste. Cook the spaghetti in boiling salted water until al dente. Drain. Pour half the sauce into a large serving bowl, add the pasta and toss. Toss in the remaining parsley. Serve immediately.