Serves 6 to 8
Swordfish is marvelous this way, but you can substitute other firm fish, such as tuna or grouper; just be mindful each fish has a different cooking time. I had these for the first time at an outdoor grigliata near the sea in Trapani, Sicily.
- 1 cup balsamic vinegar, preferably aged at least 6 years
- 18 red or white pearl onions
- 2 pounds skinless swordfish, cut into 1-inch cubes (about 30 pieces)
- 1 teaspoon kosher salt
- Freshly ground black pepper, to taste
- ¼ cup extra-virgin olive oil
- 12 fresh bay leaves
Preheat an outdoor grill or an indoor grill pan to medium-high heat. Soak eight long wooden skewers in water for 15 minutes (or use metal skewers). Bring the balsamic vinegar to a boil in a small saucepan. Lower the heat to a gentle boil, and cook until the vinegar is reduced to about ⅓ cup, about 5 to 6 minutes. Set aside.
Drop the pearl onions into a medium saucepan of boiling water, and cook until softened but still quite firm, about 4 minutes. Drain, and let stand until cool enough to handle. Slip off the skins, leaving the roots intact and the onions whole.
In a large bowl, toss the swordfish cubes and onions with the olive oil. Season lightly with salt and pepper, and toss again.
Thread the fish, onions, and bay leaves onto the skewers, dividing the ingredients evenly among the skewers and alternating them as you like. Grill the skewers until the swordfish is just cooked through, about 2 minutes on each side (4 minutes total). Serve with a drizzle of the balsamic reduction, and pass remaining reduction separately.