Soak the bag of dried pinto beans in water, at least overnight (the longer you soak the beans the shorter your cooking time will be).
Use a deep pot because the beans are going to swell up and double in size. When the beans are ready to cook, drain off the soaking water and add fresh water until the beans are covered (1-2 inches under water).
Slice a medium onion and add it to the water.
Cut the strips of bacon into about one-inch sections and put them into the water with the beans and onion.
Add the chopped jalapeno. Cover the beans and bring them to a boil. Reduce the heat and let the beans cook on low for 1-2 hours (depending on how long the beans have soaked).
Note: You must keep enough water in the pot! If the beans absorb it or it cooks away, just add more water. If you like your beans soupy, add more water. Test the beans periodically to see when they are done.