Cut a slice from the stem end of the tomatoes and discard it. Using a spoon or knife, carefully work out the pulp from the tomatoes and reserve. Do not puncture the shell of the tomatoes.
Sprinkle the inside of the tomatoes generously with salt. Let stand for 5 minutes, then turn upside down on a rack to drain.
Preheat the oven to 375 degrees.
Melt the butter and cook the onion, garlic, and celery until onion is tender. Add the curry powder and cook, stirring, for 2 minutes more. Sprinkle with the flour, then gradually stir in the chicken broth. Cook until mixture is thickened. Add the chicken and rice and season to taste with salt and pepper. Let cool slightly.
Spoon the mixture into the tomato cases and sprinkle with equal amounts of crumbs. Arrange the stuffed tomatoes on an oiled baking dish and bake for 15 to 20 minutes until tomatoes are piping hot and cooked.