Vegetarian Split Pea Soup

In a large saucepan, combine the first 9 ingredients; bring to a boil. Reduce heat; cover and simmer until peas are tender, about 1 hour, stirring occasionally. , Add salt and pepper; simmer 10 minutes longer. Remove soup from heat; cool slightly. Process in batches in a blender or food processor until smooth; return to pan and heat through. If desired, garnish with carrots and green onions.