Columbian Vegetable Soup Ajiaco Negro by Serious Eats

– 2 large russet potatoes, peeled and cut into 3/4-inch dice (about 1 1/4 pounds)
– 1 medium carrot, peeled and cut into medium dice (about 5 ounces)
– 1 cup fresh or frozen peas, divided
– 1 1/2 cups cooked dried or canned fava beans, or 1 1/2 cups raw fresh fava beans, divided
– 1 large ear yellow corn, shucked and cut into 6 pieces crosswise
– 1 1/2 quarts homemade vegetable stock or an equivalent amount made with Better Than Bouillon vegetable base or No Chicken Base
– Kosher salt and freshly ground black pepper
– 1/4 cupminced fresh cilantro leaves