In a large shallow dish, like a pie plate, whisk together the milk, egg, vanilla, cinnamon, & sugar. Dip the taco size flour tortillas in, one at a time, saturating both sides with French toast batter. Place the coated tortillas in a hot buttered skillet. Cook on each side for a couple minutes, until the French toast tortillas have lightly browned. Remove from the pan & set aside. I like to put mine on a wire rack lined baking sheet & I keep it in the oven at 200 degrees to keep them warm while I'm preparing the remaining tortillas & cooking my scrambled eggs.