Preheat oven to 425℉. Arrange chopped sweet potato on a rimmed baking sheet. Drizzle olive oil over sweet potato. Season with the salt, pepper, and cumin. Toss around to mix the seasonings together and then arrange into one even layer again. Roast for 25 minutes, tossing halfway through.

Meanwhile cook ground beef in a large skillet and cook over medium high heat breaking it up into small pieces. Cook for about 8-10 minutes or until cooked through and no pink is visible. Add black beans, cumin, oregano, and salt and stir in. Transfer to a bowl and keep near the stove. Wash and dry skillet to use for quesadillas.

In a medium bowl, mash avocado with a fork. Add plain yogurt, lime, juice, and salt and mix well. Store in fridge until ready to use.

Arrange an assembly line of tortillas, the beef and bean mixture, roasted sweet potatoes, cubed avocado, and cheddar cheese. Add a scoop of the cooked ground beef and bean mixture to one half of the tortilla, followed by a little of the roasted sweet potato, a few pieces of cubed avocado, and a sprinkle of cheddar cheese. Fold over the empty half of the tortilla over the filled half. Repeat for remaining quesadillas.

Heat 1-2 tablespoons olive oil in a large skillet over medium heat. Cook quesadilla 1-2 minutes per side, reducing heat to medium low if necessary. The skillet seems to get hot quickly after the first quesadilla is cooked. Remove from heat and cut down the middle and serve. Top with avocado sauce and a squeeze of lime if desired.