1. In a bowl, whisk the soy sauce, garlic, ginger, pear, pepper, 2 sliced scallions and 2 tablespoons of the sesame oil. Add the ribs, turn to coat and let stand at room temperature for 30 minutes or refrigerate overnight, stirring occasionally.
Heat the canola oil in a large Dutch oven or enameled cast-iron casserole. Lift half of the short ribs from the marinade, brushing off the solids, and sear over moderately high heat until browned on all sides, about 5 minutes. Transfer the ribs to a baking sheet and repeat with the remaining ribs; reserve the marinade separately.
Add the onion and 2 tablespoons of water to the pot and cook, stirring to release the browned bits on the bottom, 2 minutes. Return the ribs and any accumulated juices to the pot. Add the reserved marinade, broth and 6 cups of water; bring to a boil. Cover and simmer over moderately low heat for 1 hour, skimming occasionally. Uncover and simmer for 1 hour longer, stirring and skimming occasionally.
Add the daikon, carrots and potatoes to the stew and simmer briskly until the meat is very tender, the vegetables are tender and the sauce is thickened, 30 minutes longer.
Meanwhile, in a medium nonstick skillet, heat 1 tablespoon of the sesame oil over moderately high heat. Add half of the kimchi and cook, turning occasionally, until golden and lightly caramelized. Transfer to a plate. Repeat with the remaining sesame oil and kimchi.
Serve the stew topped with the kimchi and radishes and garnished with sliced scallions. Serve with steamed rice.