Start by patting the sirloin steak dry with paper towels and season it generously with sea salt and black pepper. Allow the seasoned steak to come to room temperature for about 20 to 30 minutes.

In a medium bowl, combine ¼ cup of soy sauce, 2 tablespoons of mentsuyu, and 2 minced garlic cloves. Whisk the mixture thoroughly until blended.

Melt 1 tablespoon of salted butter in a skillet over medium heat. Add 1 tablespoon of freshly grated ginger and 1 minced garlic clove, sautéing for about 1 to 2 minutes until fragrant. Remove half of this mixture and set it aside.

Cook 1 cup of short-grain rice according to package instructions. Once cooked, mix in the reserved garlic and ginger along with the melted butter remaining in the skillet and a splash of mentsuyu.

Heat 1 tablespoon of toasted sesame oil in a cast-iron skillet over high heat. Place the steak in the hot skillet and sear for 3 to 4 minutes on each side.

In the same skillet, add the seasoned rice and sauté over medium-high heat for about 3 to 4 minutes until the bottom is lightly crispy.

Divide the crispy rice into serving bowls, then cut the rested steak into cubes and arrange it on top. Sprinkle the reserved garlic and ginger mixture over the steak.