Hearty Potato Soup
["3 medium all-purpose potatoes, peeled and cut into 1/2-inch cubes (about 2 1/2 c.)", "1 large yellow onion, coarsely chopped", "2 ribs celery, coarsely chopped", "2 small carrots, coarsely chopped", "1 Tbsp. dill weed", "1 tsp. salt", "1/4 tsp. pepper", "2 1/2 c. water", "1 Tbsp. cooking oil", "1 Tbsp. butter"]
["This soup is an inexpensive, low-fat option for a cold day."]
["potatoes", "yellow onion", "celery", "carrots", "dill weed", "salt", "pepper", "water", "cooking oil", "butter"]