Begin by melting the butter in a cast iron skillet on medium heat. Once melted, add the sliced onions and salt. Stirring frequently but let the liquid evaporate so the onions will stick to the skillet. When they begin sticking, stir more and add 1/4 cup of water to loosen the onions. Repeat this step of cooking out the liquid and letting the onions stick to the skillet. Each time the onions stick to the skillet, add another 1/4 cup of water and repeat until you get the level of browning you desire.
Serve and enjoy!