Heat a large skillet over medium heat and add the sausage. Cook until browned, breaking it into crumbles as it cooks.
Add the onion and garlic to the skillet. Cook for 2 minutes until the onion softens.
Transfer the sausage mixture to the slow cooker. Add the roasted red peppers, farro, diced tomatoes, chicken broth, oregano, salt, and black pepper.
Stir everything together, cover, and cook on low for 6 to 7 hours until the farro is tender.
Taste and adjust salt or pepper if needed. Ladle into bowls and top with fresh basil before serving.