Combine salt, sugar, 2 cups of water, 1 cup of apple cider vinegar and apple slices to kettle on stove.
Bring to a boil until salt and sugar are dissolved. Apples should be a little soft.
Add 2 additional cups of ice or cold water to the mix. Test the water temperature...if it's still pretty warm, add a more cold water or ice until it's not warm anymore...you don't want to cook your steaks before they even get into the smoker.
Add the steaks and the apple/water mix to a large bowl. Make sure the steaks are covered with liquid. If they aren't under the water, add a little more cold water until they are.
Cover bowl and refrigerate overnight.
Prepare for smoking
Start up your smoker and get the inside temperature up to about 250°.
Remove steaks from brine and cover in a seasoning of your choice.
Add your steaks to the smoker. Maintain the smoker at 225-250°.
Use a thermometer to watch the temperature of the steaks. After a few hours, they should be about 180°.
Remove from the smoker and wrap in tin foil or a pan with a lid. This will keep the steak moist.
Return steaks to the smoker and bring the internal temp of the steaks up to about 200° for the best tenderness.