Step 1Prepare a steamer.
Step 2Make the ponzu by mixing the tamari, vinegar, tangerine juice, lemon juice, and mirin in a small bowl.
Step 3Trim the bottom 3 inches off the asparagus. Place in the steamer, cover, and steam, turning occasionally to ensure even cooking, until bright green and just tender, about 5 minutes. Transfer to a serving plate.
Step 4Meanwhile, grate the radish on the small holes of a grater or against a ginger grater into a fine-mesh sieve. Squeeze the radish with your hands to remove all excess liquid. Scatter the daikon over the asparagus, then drizzle the ponzu directly over the daikon.
Step 5Sprinkle togarashi all over the asparagus and daikon and top with nori. Serve immediately.
Step 6Make Ahead: The ponzu can be refrigerated for up to 1 week.