Heat a dutch oven or braiser over medium-high heat, and add avocado oil. Add the ribs, and generously season with salt and pepper. Brown each side of the ribs.
Add in the carrots, celery and onion. Brown the soffrito over medium heat, caramelizing the vegetables for about 10 minutes.Add the garlic and tomato paste, and stir into the vegetables.
A rich, meaty sauce, perfect for tossing with pasta or serving on top of polenta or rice. Short ribs are braised for hours, until melt-in-your-mouth tender.