1In a small saucepan over medium heat, bring the vinegar to a boil and boil until reduced to about 2 Tablespoons, about 5 minutes. Turn off heat source and whisk the butter, a few pieces at a time, until it is fully incorporated. Keep warm until ready to serve.
Fish
1Brush the fish steaks on both sides with sesame oil and season with salt and pepper. Arrange fish on the grill rack and grill, turning once, until just opaque throughout, 8-10 minutes, or less to your taste.
2Transfer fish to individual plates and spoon the balsamic sauce over the top, dividing evenly. Serve immediately.