Heat 1 tablespoon of the butter in a saucepan. Add onions, garlic, apple and celery. Stir until wilted.
Add curry powder, stir. Add tomatoes, chicken broth, bay leaf, salt and pepper. Bring to a boil and simmer for 15 minutes, stirring often.
Discard bay leaf and put mixture through a food processor or food mill and process to a fine texture. If necessary, add more chicken broth to just reach pouring consistency.
Sprinkle chicken with salt and pepper.
Heat remaining butter in a nonstick skillet and add chicken. Cook over moderate heat until lightly browned. Turn pieces and cook about 5 minutes more. Do not overcook.
Pour sauce over chicken, bring to a boil and simmer for 5 minutes. Sprinkle with chopped cilantro, serve.
