If you prefer the more traditional flavour of split pea soup cooked with ham, add a bit of chopped ham or a ham bone to the soup right at the beginning.
2 cups green or yellow split peas
8 cups cold water
2 stalk celery, chopped
2 medium carrots, chopped
2 small onions, chopped
1 tsp salt
1/2 tsp black pepper
2 tbsp chopped parsley
Rinse the split peas in several changes of water, then place them into a large saucepan or Dutch oven. Add the cold water and bring to a boil over medium-high heat. Lower the heat to a simmer and cook, covered, for about 20 minutes, stirring occasionally, until the peas are soft.
Add the celery, carrots, onions, salt, pepper, and parsley. Bring back to a boil, and simmer, covered, for another 30 minutes, until the vegetables are tender and the split peas have almost completely disintegrated. Taste and adjust seasoning, if necessary.