Grind cumin, garlic, ginger, cloves, and rice to a paste, while adding a few drops of water. Set aside.
Cut raw bananas into larger than bite-size pieces, about 1 1/2 inches thick. Boil these pieces in 3 cups of water until soft. Remove from heat, drain water, and set aside.
In a deep skillet, heat oil. Add mustard seeds. When seeds start popping, add paste and curry leaves. Fry on moderate heat for 1 minute. Add 1 1/2 cups water, tamarind concentrate, and the banana pieces. Then add red chili powder, turmeric, and salt. Let cook on medium heat for 15 minutes, or until the gravy thickens.