Add 1 cup water to your slow cooker. Use kitchen shears to cut the ribs in half so they fit into your slow cooker. Place the ribs in the slow cooker and season with salt and pepper. Sprinkle the onions on top.
In a small bowl, add the apricot preserves, the ketchup, brown sugar, vinegar, and the Worcestershire sauce. Mix it very well. Spread it onto the ribs in the slow cooker. Sprinkle the onions on top.
Set the cooker to low for 8 hours or on high for 4 hours and cook the ribs.