How to Make It
In a bowl, toss the swordfish with the garlic, ginger, lemongrass, 1/4 cup of the vegetable oil and a generous pinch each of salt and pepper. Let stand at room temperature for 30 minutes.
Meanwhile, in a medium skillet, heat the remaining 2 tablespoons of oil. Add the onions and cook over moderate heat until lightly browned, about 2 minutes. Add the fennel and cook until lightly browned and crisp-tender, about 2 minutes longer.
Remove the swordfish from the marinade, scraping off the solids. Thread the swordfish, onions, fennel, zucchini and tomatoes onto eight 10-inch skewers and season the kebabs with salt and pepper.
Light a grill or preheat a grill pan. Grill the kebabs over high heat, turning, until lightly charred and the fish is nearly cooked through, about 5 minutes. Spread the Summer Herb Pesto on a large platter and arrange the kebabs on top. Drizzle lightly with balsamic vinegar, garnish with the orange zest and serve.