Step 1

Heat the butter and oil in a large Dutch oven or saucepan over medium heat. Once the butter melts, add the corn, celery, onions, bell peppers, garlic, 1 tablespoon salt, thyme and cayenne, and cook, covered, stirring frequently, until the vegetables are tender and have just begun to turn brown, 8 to 10 minutes. Sprinkle the flour over the mixture, and stir until it has all been absorbed, about 1 minute. Add 4 cups warm water, the milk, cream, potatoes and 1 tablespoon salt, and cook, stirring constantly, until the soup comes to a simmer and thickens. Partially cover and cook, stirring occasionally and adjusting the heat as needed to maintain a simmer, until the potatoes are tender, 15 to 20 minutes. Season with salt and pepper.

Step 2

Let the soup cool to room temperature, divide among four 1-quart containers and freeze for up to 1 month.

Step 3

To reheat: Let the soup thaw in the refrigerator overnight. Bring to a simmer over medium-low heat, stirring frequently, until heated through. Thin with a little water if desired, and add salt to taste.