My son and I LOVED these! I used a grill pan on the stove for my tenderloin and I carmelized the onions in a saute pan. Once I removed the onions to a bowl I simply browned the quesadillas right in the same pan, no need to add any extra oil! These are incredibly easy and muy delicioso! I served these with lightly steamed fresh corn on the cob rubbed with lime - mmmm mmmm!
I made these for dinner last night and loved them! So easy, and so delicious. I used whole wheat tortillas instaead of regular white flour tortillas and none of the taste was sacraficed. Also, I carmelized the onions in a pan on my stove to save room on the grill, and it worked out just as well. If you put the cheese layer towards the bottom of the tortilla it will melt quickly and help to bind the other ingredients together, making it easier to flip.