This tender slow-cooker pork tenderloin picks up tangy and sweet flavors from a tomato-based sauce that features the flavors of classic barbecue. Serve with crusty bread to sop up the sauce. Serve the leftover sauce with steamed hearty greens, creamy grits or shredded pork.
Combine tomato puree, green chiles, onion, water, brown sugar, vinegar, tomato paste, mustard, Worcestershire, paprika, garlic powder, onion powder, pepper and salt in a 6-quart slow cooker; stir until combined.
If needed, cut pork in half crosswise to fit inside the cooker. Add the pork to the sauce in the cooker; stir to coat. Cover and cook, flipping once, until a thermometer inserted into the thickest portion registers 145°F, 2 hours to 2 hours, 30 minutes on High or 3 to 4 hours on Low. Transfer the pork to a plate; cover with foil and let rest for 10 minutes.
Meanwhile, use an immersion blender to puree the sauce in the slow cooker until smooth, about 1 minute. (Use caution when blending hot liquids.)
Slice the pork into 1/2-inch-thick slices. Pour half of the sauce (about 2 cups) over the pork before serving. (Save any remaining sauce for another use.)