Heat oil in a large sauté pan over medium heat. Add sweet potato and cook for 7 minutes, stirring frequently. Add onion and continue cooking until sweet potato begins to brown and onion is tender. Add chorizo, stir to distribute evenly. Add black beans and continue cooking for 2 minutes, stirring to combine all ingredients. Remove from heat, cover to keep warm.

Heat a large skillet over medium heat. 

Assemble quesadillas: Place a flour tortilla on a working surface. Evenly cover with 2 tablespoons of shredded cheese. Add 2 -3 spoonfuls of sweet potato mixture and spread out evenly over cheese. Top with 1-2 tablespoons of more cheese. Cover with second tortilla and place on the hot skillet for 1 minute on each side or until the tortilla browns a little and cheese melts. Remove from heat and transfer to a cutting board. Slice in 2 or 4 pieces. Repeat with remaining tortillas and cheese. Place on a serving platter and serve with a side of fresh guacamole.