Oxtail Soup with Onions and Barley

INGREDIENTS

• 3 vegetable oil, divided
• 4 oxtails or beef shanks
• Kosher salt, freshly ground pepper
• 3 large shallots, coarsely chopped
• 2 medium carrots, peeled, coarsely chopped
• 2 celery stalks, coarsely chopped
• 4 garlic cloves, chopped
• 2 dry red wine
• 4 sprigs flat-leaf parsley
• 2 sprigs thyme
• 12 small cipolline or pearl onions
• Kosher salt
• 3 unsalted butter
• 3 large red onions, thinly sliced
• 1/3 bourbon
• 2 low-sodium chicken broth
• 1/2 pearl barley
• Freshly ground black pepper
• Prepared cornbread (for serving)