Recently an ATK episode used a 15 minute soak in one tsp baking soda mixed into 4 oz water to ensure that the bite-sized slices of pork and chicken in stir-fried dishes would not seize up into chewy pucks. There's an alchemy in the interaction of the baking soda with meat enzymes that keeps the protein strands from forcing out moisture as they contract.
The meat must be thoroughly rinsed, then patted dry, after the soaking. I tried it for the first time yesterday, making a stir-fried dinner with slices of boneless center cut pork chop. This is very lean meat and has always been chewy in the past. But this time the texture was very nice, and not mushy the way pork treated with Adolph's tenderizer is. The baking soda did not affect the taste of the meat.
I'm keeping this trick in my everyday cooking holster. ATK did not mention whether or not it helps with larger pieces of meat, like a whole pork chop, or if it benefits beef. I will try it next time I make a pork chop or something using beef round steak (which is quite lean and tends to get tough), like Swiss steak.