In a medium bowl, thoroughly mix together the refried beans and the red enchilada sauce. I used about 2/3 of the beans. You can add more if you want a thicker consistency. Set aside.
Brown the ground beef in a skillet over medium high heat. Pour off the liquid fat.
Add the taco seasoning following the directions on the package. Mine said to add 2/3 cups of water and let it simmer over medium heat for 5 minutes.
If you don't have a second skillet, remove the ground beef to a heatproof bowl so you can fry the quesadilla.
Lay out the four tortillas.
Spread one half of the tortilla with the bean/enchilada sauce mixture, avoiding the edges. You can spread the amount you would like.
Put the cooked and seasoned ground beef on top of the bean/enchilada sauce. I used a slotted spoon to be sure I wasn't adding too much extra liquid.
Sprinkle a thick layer of cheese over the meat. I used shredded taco cheese because it had additional taco seasoning. I used the entire package, adding it in even amounts to each tortilla.
Heat 1 tbsp olive oil in the frying pan at medium high heat.
Fold the empty half of the tortilla over the filled one.
Carefully drop the tortilla into the frying pan. Be careful of the splatter.
Cook until golden on one side, 3-4 minutes, and then turn it over to cook the other side and to allow the cheese to melt.
Repeat with the other tortillas, adding a bit of olive oil as necessary.
Top with sour cream and pico de gallo if desired.