Whisk mirin and ginger in a small bowl. Place steak in a shallow baking dish or pie pan. Pour mirin mixture over the steak; turn to coat. Cover and marinate in the refrigerator for at least 30 minutes or for up to 2 hours, turning occasionally.

Put a large pot of salted water on to boil for cooking noodles. Make Sesame-Soy Dressing.

Cook noodles in the boiling water until just tender, about 6 minutes. Drain; rinse under cold water. Transfer noodles to a large bowl. Add carrot and 1/3 cup Sesame-Soy Dressing; toss to coat.

Prepare a grill. Lightly oil the grill rack by rubbing it with an oil-soaked paper towel (use tongs to hold the paper towel). Grill the steak for 4 to 6 minutes per side for medium-rare, or until it reaches desired doneness. (Alternatively, brush a little canola oil over a large skillet or ridged grill pan, preferably cast-iron, and heat over high heat. Add the steak and cook for 4 to 6 minutes per side.) Transfer the steak to a cutting board. Let rest for 5 minutes, then slice thinly against the grain.

Build the salad on 4 plates starting with about 1 cup mixed greens, one-fourth of the noodle mixture, then one-fourth of the steak slices. Whisk remaining dressing again to combine, then drizzle about 4 teaspoons over each salad. Sprinkle with sesame seeds and serve immediately.

Ingredient Notes:

Mirin is a sweetened rice wine, made from glutinous rice, found in the Asian aisle of many supermarkets and in Asian markets.

Soba are Japanese buckwheat noodles.

Rice vinegar is a mild vinegar made from glutinous rice; bottlings range from clear to aged (very dark). Clear rice vinegar works best in this recipe. Substitute cider vinegar in a pinch.

Tip: To toast sesame seeds, heat a small dry skillet over low heat. Add sesame seeds and stir constantly until golden and fragrant, about 2 minutes. Transfer to a small bowl and let cool.

MAKE AHEAD TIP: Prepare recipe through Step 3 up to 2 hours ahead. Cover and refrigerate.