Toss sweet potatoes with cinnamon and butter/oil. Distribute evenly on a foil lined sheet pan. Make sure none of the potatoes are on top of each other. This will cause them to steam and get soggy instead of roasting crisply.
Bake for 15 minutes and then flip them. Add black beans to the pan. Wait another 10 minutes until they are golden and crispy.
For Pickled Green Onions
Combine vinegar, salt, sugar, and spices into a small sauce pan. Bring heat up until salt is melted. Pour over scallions and store in a jar.
To Assemble Tacos
Take 1 tortilla or lettuce leaf and add a dollop of salsa to the center, followed by at few tablespoons of beans and potatoes. Garnish with Pickled Onions. Enjoy!