Prepare rice as per package instructions, approximately 1/4 cup per serving.
Place diced sweet potatoes in a medium pot and add enough water to cover. Bring to a boil, reduce heat and simmer for approximately 5-7 minutes until fork tender. Drain and set aside.
While potatoes are cooking you can prepare the avocado-cilantro cream sauce. In a food processor process cilantro until minced. Add avocado, lime juice, salt, garlic powder, and 3 tablespoons of water and process until creamy.
In a large skillet over medium heat add the oil and onions. Saute until the onions are translucent and then add the garlic, a sprinkle of salt and pepper and continue cooking for another minute.
Add the pepper, cooked sweet potato, black beans, spinach and corn if using. Raise heat to medium high and cook for a few minutes more.
Add broth, tomato paste, lime juice, spices and salt. Taste and add any additional seasonings as necessary.
Bowls can be assembled starting with rice, sweet potato mixture and then topped with the avocado-cilantro cream sauce, chopped cilantro and green onions.