Yesterday, I made a sandwich with satisfyingly crispy bacon -- by accident.
Streaky bacon is best in a sandwich, I think. It should be of good quality, because the mass-produced stuff sheds pints of brine, and shrivels; and it should be green, because smoked bacon can become overbearingly salty when subjected to long cooking.
I use a ridged grill pan, on a low flame, turning the bacon from time to time. One has to be patient. I was starting to think that 15 minutes was long enough to wait for a bacon sandwich when my wife called me upstairs to help with a computer problem. That took a good seven minutes. When I returned to the kitchen, the bacon was crisp and brittle.
I ate it in white bread, with a little butter on one of the slices. (I softened the butter, to make it spreadable, by placing it in slivers on the bread and putting the bread under the grill for about three seconds.) On the other slice, I spread some Blue Dragon hot chilli sauce. There was nothing I would rather have eaten.