HEAT 2 Tbsp. of the dressing in large saucepan on medium heat. Add onions; cook 5 to 7 min. or until tender, stirring occasionally.
ADD curry powder; cook and stir 1 min. Add sweet potatoes, cauliflower, chickpeas, tomatoes and water; mix well.
BRING to boil. Reduce heat to medium; cover. Simmer 20 min. or until potatoes are tender. Remove from heat. Stir in remaining dressing. Serve over rice.