- Combine all marinade ingredients except ribs and thyme in a bowl. Add just enough water to make a paste and set aside.
- On a work surface, use a paring knife to remove membrane from the back of each rib rack. Rub each side with reserved marinade. Place ribs on a dish and refrigerate for 1 hour. Preheat oven to 190°C (375°F) and place oven rack in middle position.
- Wrap each rib rack in a large sheet of aluminum foil doubled with a sheet of parchment paper. Add thyme sprigs on top of ribs and fold to seal shut. Bake on a baking sheet for about 2 hours or until meat detaches easily.
- On another parchment lined baking sheet, arrange forkpierced sweet potatoes and carrots. Bake for 1 hour to 1 hour 30 minutes or until potatoes are tender.
- While cooking meat and vegetables, heat oil in a small saucepan over medium-high heat. Sauté garlic for 30 seconds. Stir in mustard. Reduce heat to low and add remaining ingredients whisking between each. Bring to a boil and let simmer over low heat for about 30 minutes or until sauce has reduced to half. Stir frequently while cooking. Set aside.
- Once vegetables are cooked, let stand 5 minutes on the counter and peel potatoes. Place peeled potatoes and carrots in a bowl. Add butter and salt to taste. Mash with a
fork and gently combine. Set mash aside to keep warm.
- Preheat oven to broil.
- When racks are cooked, remove sprigs of thyme, drain, and cut into 3-rib pieces. Place pieces on a parchment lined baking sheet. Brush lightly with reserved cola sauce and broil for about 6 to 8 minutes or until lightly caramelized. Turn half-way through cooking and brush again with sauce.
- Serve ribs with remaining sauce and sweet potato mash, and garnish with green onions, if desired.
To remove the white membrane from the back of the ribs, simply cut along the length of the membrane with a paring knife. Then pull away membrane using a wet paper towel. To barbecue ribs, set heat to medium. Place rib pieces on a pre-oiled grill and barbecue following step 7. Cooking time may vary depending on the barbecue. Do not use diet cola to make the sauce.