Preheat large deep skillet on medium heat and swirl oil to coat. Add sweet potatoes, 1/2 tbsp cumin, 1/2 tsp salt and cook for 5 minutes, stirring occasionally.
Add onion, garlic, bell pepper and cook for another 3 minutes, stirring occasionally.
Add black beans, corn, diced tomatoes, remaining 1/2 tbsp cumin and 1/4 tsp salt, taco seasoning and pepper; then stir. Bring to a boil, reduce heat to low, cover and cook for 15 minutes or until potatoes are soft.
Turn off heat. Add avocado, green onion, cilantro, lime juice and stir. Sprinkle with cheese, cover and let stand until cheese has melted.
Serve hot with Greek yogurt and salsa if desired.
Notes
Store: Refrigerate in an airtight container for up to 3 days. Do not freeze.