Fry one onion in butter until it gets translucenty, then add a handful of chopped-up celery and let it get a little discouraged.
Then add whatever spices you want (I just used a bit of salt and pepper today). And also a carrot or three, chopped up into bits that would fit into a spoon. Stir around for a few seconds, and then add a couple of handfuls of split peas (3 handfuls for every person) and then the water/broth (about three times as much the amount of the peas) and anything else you may have forgotten.
Boil or simmer until the peas are soft. Maybe a half an hour. Or a little more. Maybe less.
Then eat it.
Ways to spiff it up include a dollop of sour cream, a lovely piece of crusty bread, and a glass of fresh apple juice (NOT NECESSARILY IN THE SOUP but with it).
Nice lunch--warming and filling and enough of a meal to keep you going. Also it is very simple. And it makes you look really good when your roomies come in with their "handmade sandwiches" from the cafe on the street that uses bad tomatoes and papery bread and lots of mayonnaise. That is when you gloat.