Next make the sauce. Place all the ingredients in a small blender and whizz until well combined. Use a pestle and mortar if you don't have a blender. Set aside.
Heat the oil in a large wok. Add the onions and sauté until cooked .
Add the peppers and carrots and 1 tbsp soy sauce. Stir fry until soft.
Add tofu (if using) and beansprouts.
Add the rice noodles, sauce and curry powder. Season with salt to taste. Mix well and continue cooking for 2-3 minutes, stirring continuously to stop the noodles sticking.