Option 1: Open Flame (gas stove or grill). This is the best method for charred smoky flavor (pictured). Add the tortillas directly to the burner of your grill or gas stove over medium-low then flip with tongs once they are charred on one side. Take special care not to over-char, especially less quality tortillas, or they will become brittle and break. You still want the tortillas soft and pliable.
Option 2: Skillet. Heat a skillet (or griddle if you have one) to medium-high heat (do not grease). Heat each side of the tortilla for approximately 20 seconds until warm and soft. You are not looking for char marks with this method.
Option 3: Microwave. Working with 5-7 tortillas at a time, stack tortillas on a microwave safe plate and wrap with a damp paper towel. Microwave for 20 seconds on high, then repeat at 10 second intervals, as needed ,until warmed through.
Option 4: Oven. Create separate stacks of about 5 tortillas each, then wrap each stack in foil. Bake at 350 degrees F for 15-20 minutes or until heated through (you can bake all stacks at once).