• Heat butter and taco seasoning over medium-high heat. Add the onions and peppers, and sauté for 10 minutes. Add vinegar and cook for 4 minutes or until the vinegar is evaporated.

Using the quesadilla maker

• Preheat the quesadilla maker until the light goes on (or off, depending on the model). Spritz the plate of the quesadilla maker with cooking spray or use a tiny bit of olive oil on a paper towel to grease it. Place one tortilla on the plate then top with ½ cup of cheese, ½ of the onion mixture, and another ½ cup of cheese. Top with a second tortilla and close the lid of the quesadilla maker. Cook until the cheese is completely melted and the tortilla is crispy.
• Cut in quarters to make 6 wedges, and serve with a dollop of sour cream. Repeat with the other tortillas.

Using a skillet on the stovetop

• Heat a bit of olive oil in small sauté pan over medium heat. Place one tortilla in the pan. Sprinkle ¼ cup of cheese over half of the tortilla, and heat until the cheese is melted. Top cheese with ¼ of the onion mixture, then ¼ cup of cheese. Fold the tortilla in half and heat the whole thing for a couple minute, until the cheese is melted and the tortilla is browned.
• Cut in 3 wedges, and serve with a dollop of sour cream. Repeat with the other tortillas.