01 -
Toss the chopped onion onto the bottom of your slow cooker. Pour in the water so it covers the onion a bit.
02 -
Grab a small bowl. Stir together the brown sugar, salt, paprika, garlic powder, black pepper, and mustard powder. Sprinkle and gently rub the mixture all over both sides of the ribs.
03 -
Use paper towels to dry off the ribs really well. Set them aside for now.
04 -
Stack the rib sections into the slow cooker on top of the onions. Slather half the barbecue sauce all over the tops of the ribs.
05 -
Snap on the lid and cook. Use LOW for 8–10 hours or HIGH for 4–6 hours. The ribs are ready when the meat's super tender and easily pulls off the bone.
06 -
Dig in while the ribs are hot. Spoon on the rest of your barbecue sauce right before eating.
07 -
Want a crispy top? Move ribs onto a tray lined with parchment. Brush with more sauce. Pop under the broiler (top rack, high heat) for 5 to 7 minutes until they’re nice and browned on top.