01 - Heat olive oil in a skillet over medium heat. Add the chopped red onion and sauté for 2 minutes until softened. Add the minced garlic and cook for an additional 30 seconds until fragrant.
02 - Add the ground beef to the skillet. Cook, breaking the meat apart with a spoon, until fully browned throughout, approximately 5 minutes.
03 - Stir in the tomato paste, honey or maple syrup, soy sauce, chili powder, ground cumin, salt, and black pepper. Continue cooking for 2 to 3 minutes until the mixture is well combined and slightly thickened. Remove from heat and set aside.
04 - Wipe out the skillet and return it to medium heat. Lay out each flour tortilla flat. On one half of each tortilla, sprinkle a layer of shredded cheese, spoon on the beef filling, then add diced red bell pepper, diced green apple, and chopped cilantro if desired. Top with additional shredded cheese and fold the tortilla over into a half-moon shape.
05 - Melt butter or drizzle vegetable oil in the heated skillet. Cook the quesadillas one or two at a time, pressing down gently with a spatula. Flip once and cook until both sides are golden brown and crisp and the cheese is fully melted, about 2 to 3 minutes per side.
06 - Transfer the cooked quesadillas to a cutting board and allow to rest for 1 minute. Slice each into wedges and serve immediately while hot.