Rinse the split peas under cold water and remove any debris. Set aside.
In a large soup pot or Dutch oven, heat the olive oil over medium heat.
Add the diced onion, carrots, and celery. Sauté for about 5-7 minutes, or until the vegetables are softened.
Stir in the minced garlic, dried thyme, black pepper, and salt. Cook for an additional 1-2 minutes until fragrant.
Add the rinsed split peas and vegetable broth to the pot. Stir well to combine.
Drop in the bay leaf and bring the mixture to a boil. Reduce the heat to low and let it simmer, covered, for about 1 hour, stirring occasionally.
After one hour, remove the bay leaf. If you prefer a smoother texture, use an immersion blender to puree the soup to your desired consistency, or carefully transfer portions to a blender and blend.
Taste and adjust seasoning if necessary. Allow the soup to simmer for an additional 10-15 minutes to thicken if desired.
Serve hot, garnished with fresh herbs or croutons if you like.