Saute chicken until browned, add diced vegetables and cook until done and tender. Set aside until cooled and/or ready to use. To form quesadillas use either a press grill or stove top flat pan. Do not grease. Place one tortilla on pan/grill - top with chicken and veggie mix. Cover with cheese. Be sure to leave about 1/2" empty space at edges or ingredients will spill out when pressing. Cover with another tortilla. Cook on medium heat approx. 2-3 minutes. Flip. Cook an additional 2-3 minutes, pressing down with spatula until cheese melts and tortillas are bonded. Remove to plate and slice with a pizza cutter or sharp knife. Serve with sour cream or ranch dressing. Note: These can also be made wtih a variety of other ingredients such as beef and pork.