Rinse and drain the yellow split peas thoroughly and set aside.
Add the rinsed yellow split peas, diced onion, diced carrots, diced celery, and minced garlic to the slow cooker.
Pour in the vegetable broth and stir to combine all ingredients.
Add the dried thyme, ground cumin, smoked paprika, black pepper, salt, olive oil, and bay leaf to the slow cooker. Stir gently to distribute the spices evenly.
Cover the slow cooker with its lid and cook on low heat for 6 hours, or until the yellow split peas and vegetables are tender and the soup has thickened.
Remove the bay leaf from the soup and discard it.
Use an immersion blender to puree the soup until smooth, or leave it slightly chunky based on your preference.
Stir in the fresh lemon juice to brighten the flavors.
Taste and adjust seasoning with additional salt or pepper if needed.
Serve hot and enjoy your slow cooker yellow split pea soup.