In a blender, pour half the can of black beans and half the jar of salsa. Blend or pulse on low for 5-10 seconds. The mixture should still be lumpy.
In a sauce pan add the rest of the beans, salsa and the puree. Simmer over medium heat for 2-3 minutes.
Preheat oven and baking stone to 500 degrees. Once preheated, place tortillas on the stone and cook for 1 minute on each side, or until brown.
In a skillet (with a lid), melt ½ T butter over medium heat. Crack egg into skillet and pour in water to just cover the bottom of the pan. Cover with lid and let simmer and steam for 1-2 minutes or until the egg yolk is at the desired doneness.
Place tortillas on a plate and add cheese, lettuce, black bean puree and top with egg. Eat with a fork and knife or fold in half and enjoy it taco style.