Place the pork in your slow cooker, fat side up. Rub with garlic and top with onion (no liquid is necessary). Cook on low for 9 to 10 hours, or until pork pulls apart fairly easily. Remove to a platter to cool. Once cooled, pull the pork apart and place in a large skillet (or Dutch oven).
Prepare sauce: Combine all sauce ingredients in saucepan. Bring to a boil over medium heat. Remove from heat.
Add the sauce to the pork. Stir in the lemon juice, vinegar and tabasco (to taste). Cook over medium heat until bubbly, or place in a 375 oven for about 25 minutes.
My family likes to eat this over cooked orzo pasta or polenta, or you can certainly make some delicious sandwiches out of it too!