Cook pinto beans as described in the previous post or use leftover or canned ones.
Now this vintage cookbook I have, said to use 6 T lard, which is what I did, but I'd recommend using 3 T lard or bacon drippings instead. I had no idea how bad refried beans really was for you until I started making them today. Holy cow! Heat however many Tablespoons of lard or bacon drippings as you desire in a heavy iron skillet over medium heat. Add 2 C beans. As they fry, mash them with the back of a wooden spoon. Continue to fry and mash them until they are dry enough to shake loose from the bottom of the pan in a mass. The inner portion of this mass will or should be moist. The bottom surface will be slightly crusty. The consistency is not necessarily smooth like a puree although it may be.