Alu Gobi (Potato Cauliflower Curry)

Place the onion and water in a larger saucepan. Cook stirring until the onion is tender. Add the spices, stirring several times, and add the cauliflower and potatoes and another 1/2 cup of water. Cook, covered, over low heat until the vegetables are tender, 25 to 30 minutes. Check occasionally and add more water if necessary to keep the vegetables from sticking to the pan. Before serving, stir in the soy sauce to taste and garnish with cilantro.