How To make Mormon Split Pea Soup

2 Tablespoons Butter
1 Cup Onion

chopped
2 Cups Dried Split Peas :

washed
3 Quarts Water
3 Medium Potatoes

peeled & grated
1/2 Teaspoon Marjoram
2 Teaspoons Salt
1/4 Teaspoon Pepper
1/2 Cup Celery :

chopped
In a heavy 5 to 6 quart casserole, melt butter over medium heat. Add onions and celery. Cook 5 minutes until soft, not brown. Stir in split peas and water. Bring to a boil. Skim off any scum that may form. Add potatoes, marjoram, salt and pepper. Cook about 1 1/2 hours.