Heat a pan and add olive oil, then sear the pork chunks until browned. Add the onion and pour in the tomato sauce, mixing the ingredients well. Add 1/2 cup of cold water if needed to adjust the moisture level.

Cover an oven-safe skillet with aluminum foil. Preheat the oven to 300°F (150°C) and bake for 1 to 1.5 hours. After baking, you can let it sit for an additional 30 minutes (optional). Once done, you can serve the pork whole or shred it and soak it in the juices. Cool and store.