My mother used to make something she called "Chicken Cacciatore". Basically, it was chicken pieces cooked in pasta sauce. I've come across several different recipes for actual Chicken Cacciatore but, to be honest, that's pretty much what they amount to.
This recipe is a similar concept, only using pork loin rather than chicken.
4-5 lbs pork loin
1 24 oz. Jar of a low-sugar pasta sauce. In my local stores there's a brand called "Rao's" that's 3 gram's sugar per 1/2 cup.
2 tbsps finely minced garlic. (If you've seen my other recipes, you had to guess this was going to be in there.)
1/2 cup diced onion
Optional: 1/2 cup red wine.
Place the ingredients in a 4-5 quart slow cooker. If it will fit, you can put the loin in whole, otherwise cut it into chunks to fit.
Cook on low about 8 hours.
Stir. The pork loin should fall apart into shreds.
Serve with non-starchy vegetables or other sides of your choice. If you're not on a low-carb diet this can make a great pasta topping. If you are, you can use Spaghetti Squash.
A note: I don't really understand why the red wine makes it so much better. It doesn't really taste of wine, and I don't drink, don't care for the taste of most alcoholic drinks including wine, but it does something to the rest of it that just makes it better. You can do without it if you must, but I really think it tastes better with it.
Note2: I call the red wine optional, but when it comes down to it just about everything is optional. Recipes are a starting point. Feel free to play with them, try things. I like a lot of garlic, so I add it. If you don't, feel free to cut back or cut it out. The prepared sauce has enough of things like oregano and basil for my taste. You might like more so add them.