Heat olive oil in a large pot and sauté onion, celery, and carrots until soft. Add garlic and cook briefly.
Stir in split peas, lentils, and bay leaves. Cover with water by a few inches, bring to a boil, then reduce to a simmer. Cook until very soft and thick, stirring occasionally.
Remove bay leaves, season with salt and pepper, and stir in fresh parsley.
Serve it chunky and hearty as is, or blend with an immersion blender for a smooth, creamy traditional split pea soup.
