For vinaigrette, heat 1 tablespoon olive oil in a saucepan over medium heat. Add ginger and cook for 1 minute. Add garlic and shallots and cook for 3 minutes. Pour in the sherry vinegar. Stir to remove any browned bits on the saucepan. Add orange juice, liqueur, soy sauce, and rosemary; cook and stir until mixture has thickened and reduced by half. Remove rosemary sprig and puree mixture in a food processor. Slowly add remaining olive oil in a stream. Season with salt and pepper. Keep warm.
Rinse tuna steaks and pat dry. Grind fennel seeds, coriander seeds, and peppercorns. Transfer spices to a flat plate. Beat egg whites until slightly frothy. Season tuna with salt; dip in egg whites and then in spice mixture. Heat 1/4 cup olive oil in a heavy skillet. When smoking hot sear tuna steaks, 2 minutes per side, and set aside.
For the vegetables, heat 1/4 cup olive oil in a heavy skillet and add all vegetables to mixture. Cook for about 3 minutes. Vegetables should be coated with oil and still crisp. Toss in sesame seeds.
To serve, spoon Gilroy Garlic Vinaigrette onto the center of 6 serving plates, arrange vegetables on the plates, and top with tuna steak. Drizzle with a little more vinaigrette and serve.
A viewer or guest of the show, who may not be a professional cook, provided this recipe. It has not been tested for home use.