Remove the husks and silks from the corn. Scrub the ears well. Use a sharp knife to cut off the kernels.
Place the cobs, husks, and silks in a large pot with 8 cups of water and cover. Bring to a boil over high heat, turn down the heat to medium-low, and simmer for 30 to 45 minutes, until the broth turns golden and fragrant and tastes sweet. Strain through a sieve; you’ll need approximately 5 cups of broth.
Place 1 cup of the hot broth in a blender and add the cashews; let soak for 10 minutes.
Heat the olive oil over medium heat. Add the garlic, ginger, onion, peppers, and celery and sauté until softened, 5 to 10 minutes. Stir in the oregano. Add the corn kernels and the potatoes, and stir until coated.