In a large saucepan combine potatoes, water, onion, celery, carrot, garlic, thyme, bouillon granules, and pepper. Bring to boiling; reduce heat. Simmer, covered, for 20 to 25 minutes or until potatoes are tender. Remove from heat. Cool slightly. Place, a portion at a time, in blender container or food processor bowl. Cover and process until nearly smooth. Return all to saucepan. Stir in milk; heat just to boiling. (If desired, divide hot soup among 4 airtight containers. Store for up to 3 days in refrigerator.) Makes 4 side-dish servings.

Transfer soup to a preheated insulated vacuum bottle. (To preheat the vacuum bottle, fill the bottle with hot tap water. Cover with lid and let stand about 5 minutes. Pour out the water and immediately fill with the hot soup.) If using chilled soup, transfer to a small saucepan. Heat just to boiling, stirring often. Transfer soup to preheated bottle.