Step 1

Preheat oven to 350 degrees. Season pork with salt and pepper. Heat a medium Dutch oven (6 to 8 quarts) over medium-high. Swirl in 2 tablespoons oil. Working in batches, brown pork all over, 16 to 20 minutes total (adding remaining oil when needed). Let pork cool slightly, then cut into 1-inch chunks.

Step 2

Return Dutch oven to medium-high heat. Add onion, season with salt and pepper, and sauté until translucent, about 3 minutes. Return pork to Dutch oven along with canned chiles, salsa, and 1/2 cup water. Bring to a boil, then cover and transfer to oven. Roast until pork is very tender, about 2 1/2 hours.

Step 3

Let stand 10 minutes; skim fat with a spoon and serve with various accompaniments on the side.