Brown the turkey (recommended): Heat olive oil in a skillet over medium heat.
Add ground turkey, season lightly with salt and pepper, and cook until no longer pink, breaking it into small pieces. This adds flavor and keeps the soup from getting greasy. If you’re in a rush, you can skip this step and add the raw turkey directly.
Layer the vegetables: In the slow cooker, add onion, carrots, celery, bell pepper, green beans, zucchini, corn, garlic, and the canned tomatoes with their juices.
Add turkey and seasonings: Stir in the browned turkey, tomato paste, thyme, oregano, bay leaf, smoked paprika, and a big pinch of salt and pepper.
Pour in broth: Add the broth and stir to combine.
Cover with the lid.
Cook low and slow: Cook on Low for 6–8 hours or on High for 3–4 hours, until the vegetables are tender and flavors are well combined.
Finish with greens: About 10 minutes before serving, stir in the chopped spinach or kale. Cook until wilted and tender. Remove the bay leaf.
Brighten and taste: Stir in lemon juice, then taste and adjust salt and pepper.
Garnish with fresh parsley.
Serve: Ladle into bowls and enjoy as is, or add a sprinkle of grated Parmesan or a drizzle of olive oil for richness.