Fulton’s Slow Cooker Maple Mustard Ribs

2 large onions sliced & separated
3-4 lbs (1.5-2kg) pork baby back or side ribs
1/2 cup Fulton’s Maple BBQ sauce
2 cup (500ml) tomato sauce
1/2 cup (125ml) Fulton’s maple syrup
1/3 cup (75ml) Fulton’s granulated maple sugar
1/4 cup (50ml) Fulton’s maple mustard

Method: