How to Make It
Preheat the oven to 350°. In a blender or food processor, puree the tomatoes with their juices until almost smooth.
Heat the vegetable oil in a large enameled cast-iron casserole. Season the roast generously with salt and pepper and add it to the casserole. Brown the meat over moderate heat until crusty all over, 10 to 12 minutes. Transfer the roast to a platter.
Melt the butter in the casserole. Add the onions, carrots and celery and cook over moderate heat, stirring, until barely softened, about 5 minutes. Add the garlic and cook until fragrant, about 2 minutes. Sprinkle in the flour and cook, stirring, until incorporated, about 1 minute. Gradually stir in the diluted beef broth. Add the tomatoes, soy sauce, chili sauce and sugar and bring to a simmer.
Put the roast back in the casserole. Cover the casserole and cook the meat in the oven for 2 hours, turning it halfway through. Add the potatoes, cover and cook for about 30 minutes longer or until both the meat and the potatoes are fork-tender but not falling apart.
Transfer the roast to a cutting board and cover loosely with foil. Using a slotted spoon, transfer the vegetables to a large deep platter, cover and keep warm. Thickly slice the meat across the grain and arrange it on the platter. Return the casserole to high heat and boil the sauce, skimming frequently, until thickened and reduced to about 5 cups. Season the sauce with salt and pepper, pour it over the meat and vegetables and serve.