1/2 pound shelled fresh fava beans, or shelled fresh lima beans, or 1 2/3 cups thawed frozen, or a combo
3 leeks (about 1 1/2 pounds)
2 tablespoons unsalted butter
4 cups chicken broth
1/2 pound asparagus
1/2 pound small white mushrooms
2 ounces Parmigiano-Reggiano
1 cup shelled fresh or thawed frozen green peas
If using fava beans, bring 1 quart salted water to a boil over high heat. Add the shelled fava beans and blanch for 1 minute; immediately transfer them with a slotted spoon to a bowl of ice and water to cool. When they are cool enough to handle, gently peel the skins from the beans.
Trim off and discard the green part of the leeks, leaving about 5 inches.
Cut the white parts in half lengthwise and then into 1-inch pieces (about 3 1/2 cups); rinse them well and pat them dry.
Melt the butter in a large skillet over medium heat. Reduce the heat to medium-low; add the leeks and cook 5 minutes or until they have softened.
Meanwhile, bring the broth to a boil in a 4-quart saucepan. Trim the asparagus. Peel the stems if they are thicker than 1/3-inch; slice the asparagus crosswise into 1-inch lengths (about 1 1/3 cups). Clean, trim, and quarter the mushrooms (about 2 2/3 cups).
Add the asparagus and mushrooms to the leeks and cook for 2 to 3 minutes more, or until almost tender. Microplane-grate the cheese (about 1 1/3 cups) or grate on the fine side of a metal grater (about 2/3 cup).
Add the leek mixture to the chicken broth along with the favas and peas. Bring to a boil over high heat, reduce the heat to low, add the dumplings and cook for 8 to 10 minutes, until they are cooked through. Stir in the cheese and serve.
Bread Dumplings: Beat 2 large eggs in a medium bowl until frothy. Stir in 2 cups fresh white or whole wheat bread crumbs, 2 ounces Parmigiano-Reggiano cheese (about 1 1/3 cup microplane grated or 2/3 cup grated on the fine side of a metal grater), and 2 tablespoons chopped fresh flat-leaf parsley leaves. Roll into 12 balls. Cook in soup as directed above.