In a nonstick skillet, saute onion in oil. Add the carrots, water, salt, pepper and curry. Bring to a boil. Reduce heat; cover and simmer for 6 minutes or until vegetables are tender. Uncover; cook for 8 minutes or until liquid has evaporated. Cool.
Transfer to a food processor or blender; cover and process until smooth. Add mayonnaise and mustard; mix well. Serve with vegetables.