Preheat the oven to 450°F. Line two baking sheets with aluminum foil.
Make the miso mustard dressing. Combine all the dressing ingredients in a small bowl.
Chop the tofu into ½" cubes. In a medium bowl mix the tofu with ⅓ cup of the miso mustard dressing. Allow to marinate 5-10 minutes. Arrange the tofu on one of the baking sheets and bake for 25-30 minutes.
Meanwhile, peel and chop the butternut squash into a ½" dice. Arrange on the second baking sheet and sprinkle with curry powder. Bake in the oven with the tofu for 15-20 minutes, until soft.
While the squash and tofu are baking, cook the buckwheat. Add the buckwheat groats and 2 cups of water to a medium pot and bring to a boil, reduce the heat to low and cook 10-15 minutes, until the water is evaporated. Watch the buckwheat carefully to avoid overcooking.
While the buckwheat is cooking, de-stem the kale and chop into bite-sized pieces. Place the kale in a large bowl and massage with 2 tablespoons of the miso dressing. For best results, massage the kale several minutes.
When all the ingredients are finished cooking, assemble the bowls. Place a bed of kale in each bowl, then add a scoop of buckwheat. Top with squash and tofu. Drizzle with any leftover dressing and sprinkle with sesame seeds. Enjoy!