Preheat the oven to 400 degrees Fahrenheit. Scrub and rinse the sweet potato and cut away any bad spots. Chop the sweet potato into cubes about ½ inch square. Spread on a baking sheet and coat with coconut oil. Roast in the oven for about 30 minutes, stirring occasionally. Depending on your oven and the size you chop the sweet potato, roasting could take more or less time, just check on them often, they will be ready when they are soft and have started to brown. Meanwhile, warm the refried beans on the stovetop, and warm the taco shells if you like. When the spuds are done, build your tacos starting with beans, then add the roasted sweet potatoes, greens, avocado, shredded carrots, salsa and hemp seeds.