Combine the chopped onion, carrots, celery, green beans, corn, potatoes, red pepper, Italian seasoning, and garlic powder in a 6-quart or larger slow cooker crock.
Remove lid and stir in baby spinach and fresh lime juice. Taste and season with additional salt and black pepper, if desired. Cover and let simmer for 5 minutes or just until the spinach is wilted.
Serve immediately garnished with lime slices and fresh parsley, if desired. Enjoy!