Place all of the ingredients, including the liquid from the beans, into a medium saucepan and simmer on low heat for 5-8 minutes, until warmed through. Drain the beans (don't rinse them though!) and set aside.
To prepare the sweet potatoes:
Preheat the oven to 425°F.
In a large mixing bowl, toss the sweet potato rounds with the olive oil, cumin, salt, and pepper. Spread in an even layer on a baking sheet lined with parchment paper.
Roast the potatoes for 10 minutes, flip them and roast 10-15 minutes more until they are crispy and golden brown on the outside.
To assemble the wraps:
Spread the tortillas with guacamole, leaving a 2-inch border. Divide the spinach, sweet potatoes, black beans, tomato, and onion evenly among all 4 tortillas, piling the toppings in the center of each.
To form the wraps, fold two sides of the tortilla over the filling, then roll tightly, ending seam side down. Cut in half down the center to serve.
If your tortillas don't feel flexible when you remove them from the package, you'll want to heat them, especially if you're using gluten-free tortillas, which are prone to breaking. Wrap the tortillas in a damp paper towel and heat them in the microwave for 15-20 seconds. If you don't have a microwave, you can heat them in a skillet too.