Oxtail Soup with Onions and Barley

Heat 1 tablespoon oil in a large heavy pot over medium-high heat. Season oxtails with salt and pepper. Working in 2 batches, cook until browned on all sides, adding 1 tablespoon oil between batches, 10-15 minutes per batch; transfer to a plate. Add remaining 1 tablespoon oil to same pot. Add shallots, carrots, and celery. Cook, stirring occasionally, until golden brown, 8-10 minutes. Add garlic; cook, stirring, just until fragrant, about 1 minute. Add wine; cook, scraping up browned bits, until reduced by half, 5-8 minutes. Add parsley, thyme, and 4 cups water; return oxtails to pot. Bring to a boil, reduce heat, cover, and simmer, stirring occasionally, until meat is fork-tender, 3-3 1/2 hours. Using a slotted spoon, transfer oxtails to a plate. Let cool slightly; shred meat, discarding bones. Strain stock through a fine-mesh sieve into a large bowl or measuring cup (discard solids). Skim fat from stock; add water if needed to measure 4 cups. DO AHEAD: Oxtail stock and meat can be made 2 days ahead. Let cool. Cover separately; chill. Rewarm before using.