Heat 1 tbsp olive oil in a nonstick pan over medium heat. Add the chopped onion, red bell pepper, and green bell pepper. Sauté for about 10 minutes, stirring occasionally, until the vegetables are soft and starting to turn golden at the edges. Remove from the pan and set aside.

In the same pan, melt 1 tbsp butter over medium heat. Add the cubed chicken and taco seasoning. Toss to coat and spread into a single layer. Cook for about 15 minutes, turning occasionally, until the chicken is fully cooked through to an internal temperature of 165°F and golden on the outside.

In a separate nonstick pan over low heat, warm one flour tortilla for about 30 seconds per side until pliable and slightly golden. Warming the tortilla prevents cracking when folded and improves the final texture.

Lay the warmed tortilla flat in the pan. Spread 1/2 cup of shredded cheddar cheese over one half only. Layer on half the cooked chicken, half the sautéed vegetable mixture, and 2 tbsp of drained corn.

Fold the empty half of the tortilla over the filling. Press gently with a spatula and cook on low heat for 2 to 3 minutes until the cheese melts fully. Flip carefully and cook the other side for 1 to 2 minutes until golden brown and crisp. Keep the heat low to avoid burning before the cheese melts.

Slide onto a cutting board and cut into three triangles. Repeat with the second tortilla and remaining ingredients.

For the optional salsa: add the tomato, onion, white vinegar, cilantro, and a pinch of kosher salt to a food processor. Pulse for about 1 minute until combined. Serve right away alongside the warm quesadillas.