Heat 1 tablespoon of vegetable oil in a large skillet over medium-high heat. Once shimmering, add finely chopped red onion and bell peppers. Sauté for about 5 minutes until tender.

In the same skillet, add seasoned ground beef and taco seasoning. Cook for 5–7 minutes until browned. Drain excess grease.

Lay out four large flour tortillas. Distribute sautéed vegetables over each tortilla, followed by cooked ground beef. Sprinkle shredded cheeses and add jalapeños and cilantro.

Place another tortilla on top of each loaded tortilla, press down gently to seal.

In the same skillet, heat another tablespoon of vegetable oil. Cook quesadillas for 3–4 minutes on each side until golden brown and cheese is melted.

Remove from skillet, let cool slightly, then slice into wedges for serving.