For cleaning the chuño

• 3 cups ground black chuño
• Cold water for soaking

For the lawa

• 1/4 cup vegetable oil
• 1 medium onion, finely chopped
• 2 tablespoons minced garlic
• Ground oregano, to taste
• Salt and pepper, to taste
• 3 medium potatoes (yellow or peruanita), cut into 2 to 3 cm pieces
• 1/2 kg fresh fava beans, peeled
• 2 to 3 liters water or broth
• Finely chopped parsley, for serving