instruction:
In this task the focus is on physical knowledge about the world. Given the provided goal task in the input, describe a process that would lead to the asked outcome. This process often involves physical motions with objects, such as moving them, arranging them in a certain way, mixing them, shaking them, etc. 
question:
To prevent water from growing bacteria, you can
answer:
Use a small amount of vinegar or bleach


question:
To make the best use of space while packing,
answer:
tightly roll up each article of clothing instead of folding.


question:
leek and potato soup
answer:

45 grams butter    4  leeks chopped    350 grams potatoes diced    1 litre chicken stock    Instructions    In a saucepan, melt half the butter over low heat. Add the leeks and cook, stirring occasionally, until softened, about 5 minutes. Add the potatoes and cook for 3 minutes.    Increase the heat to medium, pour in the stock and bring to boil. Reduce to a simmer, cover, and cook until the leeks and potatoes are tender, 35 to 40 minutes. Remove the pan from the heat and add the remaining butter in small pieces, stirring until it’s all incorporated.    Season with sea salt and pepper to taste. Transfer to a blender and puree until smooth. Serve in warm bowls.