Add the olive oil to a saute pan and kick the heat up to high. Once the oil has warmed up add the sweet potato chunks and cook on medium-high for 10 minutes stirring frequently to prevent burning.
Mix all the spices together (the salt, cumin, fennel, smoked paprika, garlic powder, onion powder, and cayenne pepper. Add the spice mixture to the sweet potatoes and stir to mix.
Add the lime juice and water to the saute pan and stir. Then turn the heat down to medium-low, cook for another 10 minutes until most of the liquid is gone and sweet potatoes are tender.
Add the black beans to the saute pan and stir to mix everything together and turn off the heat.
While the sweet potatoes are cooking, prep the tortillas. Put another saute pan on the stove and turn the heat up to high. Cook each tortilla on high for about 1-2 minutes per side, more if you prefer a crunchier taco shell. I like to cook them until they just start to get little brown spots.
To serve:
Add a scoop of the sweet potato and black beans to the taco shell.
Add your favorite salsa, avocado slices, sweet mini pepper slices, and/or cheese