In a small bowl combine mustard, salt, turmeric, cumin, coriander, and cayenne pepper. Set aside.
In a wok or extra-large skillet heat oil over medium-high heat. (Add more oil if necessary during cooking.) Add cauliflower; cook and stir for 6 minutes. Add sweet pepper and green onions; cook and stir for 1 minute. Reduce heat to medium. Add mustard mixture. Cook and stir for 30 seconds. Carefully stir in broth. Cook and stir about 1 minute more or until vegetables are heated through. Serve immediately.