This method takes much less time than the a slow cooker and gives much better results. I prefer a bone-in shoulder roast, also known as a “picnic” shoulder. This is an inexpensive cut of well-marbled meat, and the bone adds flavor.
Preheat oven to 400, For a 6-8 pound cut, make a spice blend of 3 tablespoons each paprika, granulated garlic, and black pepper, and about a tablespoon of salt. You can add a couple of tablespoons of brown sugar to this if you like, but I don’t. I don’t like to use much salt, either, because salt and sugar draw moisture from the meat. Besides, you’re going to get plenty of sugar and salt in any barbecue sauce, no matter who makes it.
Mix this blend with about 1/2 cup vegetable oil and rub over meat. Peel and chop into quarters 2 white onions, separate, and place in the bottom of an oven roaster. Put meat on top on onions, a set on a mid/low rack; I place a saucepan of water alongside the roast to help keep it moist.
After an hour, reduce heat to 250. After another two hours or so, when the pork is fork-tender, remove from oven, cool enough to handle, discard fat and bone, and reserve some of the pot liquid (without the fat). Shred meat into a lidded container and add enough of the reserved liquid for even moisture.