i am making pork loin and i want it to be tender and flavorful without losing a lot of moisture, my go to method is to Dice the pork loin into bite sized cube, then chop onions into very small pieces and mix it in well with the pork loin, then i add 40% water, 40% rice vinegar, and 20% soy sauce to the mix (about 2 cups in total liquids), then i throw in some chopped mushrooms on top, compress the cold mixture, and cover it with lettuce to reduce evaporation and prevent oxygen flow. is this a bad way of doing it? i made it up myself so im not sure, can anyone give me some decent advice on how to make it better, i plan to simmer it in the marinate afterwards, along with garlic and parsley
A couple of things to consider:
Pork loin is super lean so the only way you are going to keep it moist and flavorful is to cook it to the correct temperature. Cutting it in cubes increases the potential for overcooking.
Marination is a surface treatment. It flavors the surface of your product only.
It sounds like you are making a brine (though I worry about vinegar, both from a flavor perspective and because it has the potential to impact the texture of your pork). Brine contains salt. Salt penetrates the surface (pretty much the only thing that penetrates the surface) and will both season the product and help keep it moist. You don't need to brine more then a couple of hours.
The mushrooms probably are not adding much.
Evaporation and "oxygen flow" is not something to worry about, so I think the lettuce is unnecessary.
For better advice, you would need to clarify. Do you want to brine (to help prevent drying) or do you want to marinate (to flavor your pork). You've got a brine here.