To make the guacamole, use a spoon to scoop the avocado out of its skin and put it directly into a medium bowl. Add the lime juice, nutritional yeast, garlic, and chili powder and mash with a fork or potato masher to the desired consistency. Add the beans, bell pepper, cilantro, green onion, and chile and stir to combine. Season with salt and pepper to taste. Cover and store in the refrigerator until ready to serve.
To cook the sweet potatoes, preheat the oven to 400 degrees F. Using a fork, pierce each potato in several places on all sides and put them on a baking sheet. Bake for 30 to 40 minutes (turn them over after 20 minutes), until the sweet potatoes are soft and can be easily squeezed. Alternatively, to cook the sweet potatoes in the microwave, put them in a glass or ceramic baking pan and microwave for 10 to 15 minutes, until the sweet potatoes are soft.
Using a sharp knife, cut a slit down the length of each sweet potato. Gently squeeze the sides toward the middle to open the sweet potatoes, then put them on a large platter or on individual plates. Alternatively, cut each potato in half lengthwise and put them cut-side up on a platter or plate.
Top each sweet potato with half of the guacamole. Serve hot.