In a small bowl, mix together the chicken broth, soy sauce, sugar, salt, and pepper to make the sauce. Set aside.
Fill a large bowl or pot with hot, just boiled water and add rice noodles. Let noodles soften until just tender, about 5 minutes. Drain, rinse with cold water, and drain again.
Heat a large wok over high heat and add oil. Once the oil and pan are very hot, add the garlic, ginger, and curry powder. Stir-fry about 10-30 seconds, just until fragrant. Stir in the red onions and cook about a minute. Add the bell pepper slices and cook another minute. Stir in the Napa cabbage and cook for an additional 3 minutes, until all the vegetables are heated through and beginning to soften.
Toss in the noodles and sauce. Cooked until just heated through and mixed. Serve immediately or at room temperature.