In the slow cooker, combine the onions, garlic, ketchup, tomato paste, Worcestershire sauce, chili powder, balsamic vinegar, and honey. Season with salt and pepper, stir well, and cook on high for 1 hour.
Towards the end of the hour, heat a large pan over medium-high heat. Add the oil. Season the lamb with salt and pepper. Sear the lamb on all sides, turning it and allowing it to rest on the edge of the pan as needed. It’s ok if you can’t get the ends browned, but you want a nice sear on as much of the exterior as you can get. This should take about 10 minutes total.
Tuck the lamb into the sauce already heating in the slow cooker, and spoon some over the top. Reset the cooking time to 4 hours on high.
After 4 hours, remove the lamb to a shallow dish and, using two forks, pull the lamb into small bite-sized pieces. You can make them as small or as large as you like, depending on preference and how you plan to serve the lamb.
Spoon some of the sauce over the lamb. If you want to serve it in sandwiches, pile it onto the buns, and spoon some of the Sriracha Mayo on top. You’ll likely have some leftovers, which is a very good thing.
Notes
If you want to take a super shortcut, use 3 cups of your favorite barbecue sauce. But if you have a handful of extra minutes, make the balsamic barbecue sauce in this recipe. And, because we are in slow cooker mode, not only is the lamb made in the slow cooker, but the barbecue sauce is as well!
Pulled slow-cooked lamb keeps really well in an airtight container in the fridge, and I would even suggest making extra to use for the week. Store leftover lamb in a sealed container for up to 1 week. Reheat it in the crock pot or in a pot over low heat with its liquid.