Step 1

Place the potatoes and water in a 4 1/2-quart saucepan or Dutch oven, and bring the water to a boil. Reduce the heat to low, cover the saucepan with a lid, and simmer the potatoes for 20 minutes.

Step 2

Meanwhile, place the oil in a 9-inch or 10-inch skillet, and heat it over medium-high. When the oil is hot, add the onion, celery, carrot, red bell pepper, and thyme or oregano leaves. Cook, stirring constantly, until the vegetables are just tender, about 5 to 8 minutes. Remove the skillet from the heat, and set aside.

Step 3

When the potatoes are tender, remove the saucepan from the heat. Using a slotted spoon, transfer 1 1/2 cups of the potatoes to a blender. Add the milk to the blender, and process until the mixture is smooth.

Step 4

Pour the blended mixture into the saucepan containing the remaining potatoes and their cooking liquid. Stir in the corn and the reserved cooked vegetables (from Step 2).

Step 5

Place the saucepan over medium heat, and warm the soup through before serving it, about 5 to 10 minutes. Serve hot.