Pat the hanger steak dry and season generously with kosher salt on all sides. Let it come to room temperature.
In a medium mixing bowl, toss together ginger, scallion, ponzu, rice vinegar, and neutral oil in a small bowl. Season with salt and finish with pepper.
Heat a cast iron skillet over high heat with neutral oil until just smoking. Add in your steak, and sear 3 to 4 minutes per side for medium-rare, or use an instant-read thermometer to reach 130-135°F for medium-rare, basting with the butter in the last minute. Transfer to a cutting board to rest for 5 to 10 minutes and then slice against the grain and at an angle.
Bring the same cast iron skillet to low heat, keeping the steak and butter juices in the pan. Add in your halved cherry tomatoes, cook for about 2 to 3 minutes, just until they blistered and soften, but still keeping the integrity of the tomatoes. Toss in your butter until melted and season with salt and pepper.
On a plate, add your tomatoes and any sauce, top with your sliced steak, finished with your ginger-scallion ponzu sauce. Serve as is, or alongside some white rice.
Notes
Steak Subs: You can adjust with ribeye steak, flank steak, or NY strip steak in place of hanger steak.
Doneness: We like to use a thermometer at 130-135°F for medium-rare.
Prep: You can prepare this ginger scallion ponzu sauce up to 2 days ahead, but prepare the steak at the time of serving.
Storing: Store in an airtight container in the refrigerator for up to 2 days. Warm up in a pan.