Add the onions and sauté until they are golden brown. You may sprinkle a little water to avoid them from burning. Add the tomatoes, chilli powder, turmeric powder and the ground paste and simmer for a while. Meanwhile, add 1¼ cups of water to the curds, and whisk well. Add this to the subzi and bring to a boil. Add the sautéed bhindi and salt and simmer for 5 more minutes. Serve hot.