Things You'll Need
1 stick of butter
7 to 8 qt. pot
2 lbs. onions, sliced, or 1 lb. onions and 1 lb. sliced leeks, white parts only
5 qts chicken broth, homemade or from the store
5 to 6 lbs potatoes, peeled, rinsed and coarsely diced
Blender, or immersion blender
Chives or chopped parsley (optional)
The first step in preparing a meal for a large group is to work out how much food you'll need to make. Portions may be smaller as part of a several course meal or a buffet, but otherwise soup is usually portioned in 8-ounce bowls. A simple calculation gives a total of just over 6 quarts of soup, to feed 25 people. Armed with this information, you need only scale up your favorite recipe, or find one that's already big enough.
Unwrap a stick of butter and put it in the soup pot. Place the pot on your stove over moderate heat until the butter melts.
Add the onions and the leeks, if you are using them. Sweat them slowly in the butter, stirring frequently with a wooden spoon. Do not let the onions brown.
Pour the chicken broth over the onions once they are translucent and aromatic. Add the potatoes, the turn up the burner and bring the pot to a simmer.
Simmer the soup until the potatoes are well-cooked and tender, about 15 to 20 minutes from the time the pot comes up to temperature. Taste one of the potatoes to make sure they are fully cooked, before proceeding.
Remove about one-fifth of the potatoes from the pot. Puree the remainder in small batches in your blender, or use an immersion blender to puree them in the pot. Continue until all the potatoes in the pot are pureed.
Check the thickness of the soup. It should be very hearty, but not so thick that it holds its shape when ladled into a bowl. If the soup is too thin, add some of the reserved potatoes and puree them. Repeat until the desired texture is reached. Any leftover potatoes can be refrigerated for another use.
Taste the soup and adjust the seasoning with salt and pepper to suit your taste. Store-bought broth can be quite salty, so do not add any salt before tasting. Garnish with chopped chives or parsley, if desired, and serve hot.
The same soup, served cold, is the French classic called Vichyssoise.
The basic recipe may be enhanced by the addition of bacon, colorful vegetables or cheese, as desired.