Slow-Cooker Short Ribs

Season short ribs with salt and pepper. Heat oil in a large Dutch oven over medium-high heat. Working in 2 batches, brown short ribs on all sides, about 8 minutes per batch. Transfer short ribs to slow cooker and pour off all but 3 tablespoons drippings from pot. Meanwhile, whisk soy sauce, water, brown sugar, rice wine vinegar, sesame oil and red pepper flakes. Add carrots and onions to pan, and cook, mixing occasionally until browned. Add garlic and ginger and brown until fragrant, 1 minute more. Remove from heat and deglaze with reserved soy sauce mixture, scraping up any brown bits from the bottom. Pour this mixture into the slow cooker.  Cover slow cooker and cook on low for 9 to 10 hours, or on high for 4 to 5 hours, or until the meat is very tender and falling off the bone.  Garnish short ribs with toasted sesame seeds and green onions. Spoon sauce over rice and serve.