In a large bowl, combine all ingredients except for the oil and ribs. Whisk to combine and dissolve the sugar. Set aside.
If using a rack of ribs, cut into portions that contain 1-2 bones.
Heat oil in a skillet over medium-high heat. Sear the ribs on each side until well browned, 4-6 minutes per side. Be sure to not crowd the skillet or the ribs will steam and not brown.
Once browned, place the ribs in a 4-6 quart slow cooker.
Pour the prepared sauce over the ribs, making sure all are coated.
Cover with lid and cook on low 6-8 hours. The ribs will be fall-apart tender. If a thickened sauce is desired, pour into a small kettle and simmer for 10-15 minutes to condense and thicken.