In a bowl, whisk together the flours. Make a well in the middle and add water, mixing with a fork to bring the dough together. Knead on a lightly floured surface, adding more flour as needed until the dough is smooth but no longer sticky. Let rest, covered with plastic wrap or a damp towel, for 30 minutes.
Form the dough into six balls of equal size. While working with one, keep the rest covered.
Flatten one ball to about 1/2 inch thick. Liberally dredge the dough in flour and set pasta roller to the lowest setting. Run dough through the first four settings, then cut using the spaghetti roller.
Toss pasta with 1 teaspoon flour and set aside while you finish rolling the rest of the dough.
In a medium pot, bring 4 cups of water to a boil with 2 tablespoons salt. Boil the fresh pasta in two batches, removing with a slotted spoon or strainer when done, approximately 1-2 minutes.
In a medium-sized salad bowl, whisk together the miso, tahini, mirin, garlic and water until smooth. Pour the buckwheat noodles into the sauce, along with any veggies or tofu. Toss together until well combined. Finish with sesame seeds and enjoy!