In a large pot, heat the olive oil over medium heat. Add the chopped onion, garlic, carrots, and celery, and sauté until the vegetables are softened, about 5-7 minutes.

Add the rinsed split peas, vegetable broth, dried thyme, and bay leaf to the pot. Bring the mixture to a boil.

Once boiling, reduce the heat to low, cover, and simmer for about 45-60 minutes, or until the peas are tender and the soup has thickened.

Remove the bay leaf and season the soup with salt and pepper to taste. If desired, stir in the lemon juice for added brightness.

Use an immersion blender to puree the soup to your desired consistency, or leave it chunky.

Serve hot, garnished with fresh parsley.