Heat the olive oil in a large pot over medium heat. Add the chorizo slices and cook until sausage is lightly browned, about 10 minutes. Remove sausage from pot with slotted spoon and reserve. Add onions, salt and pepper to pot and cook over medium low heat until translucent, about 10 minutes. Add garlic and cook 1 minute to release its aroma. Stir in carrots and celery and cook five minutes. Add potatoes, split peas, stock or water and bay leaf and bring to a simmer. Cook about 45 minutes, until peas are soft. Add back reserved chorizo slices and simmer 5 minutes to combine flavors. Stir in parsley and sage and serve.