Season the ribs with salt and pepper. Heat a 5-qt. Dutch oven over medium-high heat. Add 2 Tbsp. olive oil and heat for one minute.
Pour off any excess fat from the pan and add 1 Tbsp. olive oil, heat for a minute.
Add the onions and sauté until translucent. Add the garlic and sauté 1 minute longer. Add the tomato paste and sauté for about a minute while mixing well. Transfer onion mixture to slow cooker and toss to coat ribs.
Add all the other ingredients to the crock, cover and cook for 10 hours using the Auto setting or 2 hours on High and 8 hours on Low. At end of the cooking time, the ribs should be tender and fall off the bone.
Remove ribs from the liquid, set aside and cover with foil to keep warm.
Remove and discard bay leaves and carefully place the mixture in a blender and puree until smooth. Serve immediately.
Extra green tomato relish can be stored for two weeks in a refrigerator.
Add pureed liquid back to slow cooker crock; add ribs and serve when ready.