Using a heavy bottomed dutch oven or pot, heat the oil and curry powder over medium heat, stirring, until fragrant, for about 1 to 2 minutes. Stir in the carrots, celery, cauliflower and onions; toss to coat. Cook, stirring frequently, for about 10 minutes. Pour in the chicken broth. Stir and bring to a boil. Reduce heat and simmer until the vegetables are very tender, for about 10 minutes. Remove from the heat and let stand for a few minutes.