In a large bowl, whisk together the miso, soy sauce, honey, sesame oil, ginger, garlic, and rice vinegar until smooth.
Add the steak and turn to coat well. Cover and refrigerate for at least 30 minutes or up to 8 hours.
Remove the steak from the refrigerator about 20 minutes before cooking. Discard the marinade and pat the steak dry with paper towels.
Heat the neutral oil in a large cast-iron skillet over medium-high heat until just smoking.
Cook the steak for 3 to 5 minutes per side, depending on thickness, until deeply browned and cooked to your preferred doneness (125°F/52°C for medium-rare).
Transfer to a cutting board and let rest for 10 minutes.
Meanwhile, reduce the heat to medium. Add the beef broth, soy sauce, honey, and miso to the same skillet. Whisk until the miso dissolves, scraping up any browned bits from the bottom of the pan. Simmer for 2 to 3 minutes, until the glaze lightly thickens.
Slice the steak thinly against the grain.
Arrange on a serving platter and spoon the warm miso glaze over the top.
Sprinkle with the green onions and sesame seeds. Serve with lime wedges, if desired.
Notes
Erren’s Top Tips
Don't marinate longer than 8 hours; the steak gets plenty of flavor without an overnight soak.
If a long skirt steak doesn't fit comfortably in your skillet, cut it into two pieces rather than crowding the pan.
Miso and honey brown quickly, so lower the heat if the surface starts getting too dark.
Let the steak rest before slicing so the juices have time to settle.
Always slice skirt and flank steak against the grain.
Keep the glaze slightly loose — it thickens as it sits.
Variations & Add-Ins
Add chili crisp, sambal, or sriracha to the glaze for heat.For more brightness, stir fresh lime juice into the finished glaze.You can also grill the steak over high heat and make the glaze separately in a small saucepan.
Storage & Freezing
Store leftover steak and glaze in the refrigerator for up to 3 to 4 days. Keep them separate when possible and gently reheat the steak with a little glaze or broth to avoid overcooking it.Freeze sliced cooked steak for up to 2 months. Thaw overnight in the refrigerator before reheating.