In a large bowl filled with warm water, soak 1 rice paper wrapper for about 20 seconds or until soft. Lay wrapper out on a tea towel to absorb excess water. Transfer wrapper to a flat surface. About 1/3 from the bottom of the wrapper, create a 3-inch long row by placing some cilantro leaves followed by some red pepper, yellow pepper, snow peas, mushrooms, bean sprouts, buckwheat noodles and a little ginger. Season, to taste, with salt and pepper. Sprinkle the top 1/3 of the rice wrapper with black sesame seeds. Carefully fold the bottom of the rice paper wrapper over the vegetables. Turn in the sides and continue rolling up from the bottom.
To serve, slice the roll in half on a bias. Serve with Orange-Chili Dipping Sauce.
In a medium sized bowl, whisk together the sesame oil and rice wine vinegar. Toss the cooked buckwheat noodles in the sesame mixture. Set aside.
Whisk together all the ingredients in a mixing bowl. Allow the sauce to stand for 30 minutes so that the flavors can infuse. Serve at room temperature.
*Rice paper wrappers can be found in Asian markets and at gourmet stores. Soak and work with only 1 rice wrapper at a time because wrappers will stick together and won't be easy to work with if they absorb too much water. If not served right away, keep rolls tightly covered to prevent the rice wrappers from drying out.