This method will work with the backstrap (loin) of an red meat animal, from deer, elk, pronghorn, moose and caribou, to sheep, goats, nilgai... and yes, cows. Once made, it will keep a week in the fridge.
Weigh the meat in grams. Weigh out 1.5% of that weight in salt; you can go as high as 2%. Massage the salt into the meat well. Vacuum seal the meat and set it in the fridge for 2 days, longer if you are using elk or moose or something else thick. You cannot leave this too long -- it won't get too salty, so you can leave the meat in the fridge a week if you wanted to.
Get your smoker going; wood choice is yours. Try to keep it below 200°F. When it's ready, rinse the meat, then pat it dry with paper towels. If you have a probe thermometer, insert it into the thickest part of the backstrap. Smoke until it reaches about 135°F, which should take between 2 and 4 hours. Slice and eat.
Notes
NOTE: The curing time is so long because you want the meat to be salted all the way to the center. You can skip this long salting if you want, but the interior of meat will be bland.