Trim excess fat from the steak and cut into 1–1.5 inch bite-sized pieces. Pat the pieces dry with paper towels and season lightly with 1 tsp kosher salt and 1/2 tsp black pepper; set aside.

Make marinade

In a medium bowl, whisk together 1/4 cup bourbon, 1/4 cup soy sauce, 3 tbsp packed brown sugar, 1 tbsp Worcestershire sauce, 1 tbsp apple cider vinegar, 1 tsp Dijon mustard, minced garlic, and grated ginger until sugar begins to dissolve.

Marinate

Place the seasoned steak pieces in a resealable bag or shallow dish. Pour the marinade over the steak, press out excess air (if using a bag), and refrigerate for at least 30 minutes and up to 4 hours. Do not marinate longer than 8 hours to avoid texture changes from the alcohol and acid.

Bring to room temperature

About 20 minutes before cooking, remove the steak from the refrigerator so it comes closer to room temperature. Reserve the marinade for sauce preparation (do not use it raw on finished steak without reducing).

Bourbon glaze and finishing

Sear steak

Heat a large heavy skillet or cast-iron pan over medium-high heat until very hot. Add 2 tbsp vegetable oil and swirl to coat. Working in a single layer (cook in batches if necessary), add the steak pieces making sure not to crowd the pan. Sear without moving for 1.5–2 minutes per side until a deep brown crust forms and internal temperature is 125–130°F for medium-rare. Remove seared steak to a plate and tent loosely with foil.

Cook shallot

Reduce heat to medium. Add 2 tbsp unsalted butter to the same pan. When melted, add the finely chopped shallot and cook, stirring, for about 1–2 minutes until softened and fragrant, scraping up browned bits from the pan.

Reduce reserved marinade

Carefully pour the reserved marinade into the pan (it will sizzle). Bring to a simmer and cook for 4–5 minutes to reduce and cook off alcohol. If you prefer a thicker glaze, continue simmering until slightly syrupy.

Make slurry and finish glaze

In a small bowl, whisk 1 tsp cornstarch with 1 tsp cold water to make a slurry. Stir the slurry into the simmering marinade, then add 1 tbsp honey (or maple syrup) and a pinch (1/4 tsp) red pepper flakes if using. Simmer for another 1 minute until the sauce thickens and becomes glossy. Taste and adjust seasoning if needed (add 1/2 tsp soy sauce or a pinch of salt if too sweet).

Return steak to pan & coat

Return the seared steak pieces (and any accumulated juices) to the pan. Toss gently for 30–60 seconds to coat the steak evenly with the bourbon glaze and warm through. Remove from heat and stir in chopped parsley if using.

Rest and serve

Let the steak rest in the warm glaze for 2–3 minutes, then serve immediately. Spoon extra glaze over the steak at the table. Suggested accompaniments: mashed potatoes, roasted vegetables, or steamed rice.