Wash, peel and cut sweet potatoes into large chunks (approximately 1-2" cubes). Dice onion, garlic and peppers. Add all Ingredients except the black beans and cilantro to the slow-cooker. Cook for 8-10 hours on low or 4-5 hours on high, stirring once each hour.
Add bourbon (if using), black beans and cilantro and continue to cook for another 2 hours on low or 1 hour on high. Taste and season with more salt as needed.
Serve warm and garnish with plain Greek yogurt, more fresh cilantro, sliced avocado, and diced red onion or green onion.