Measure thickness of fish to determine cooking time; place in a glass dish. To make vinaigrette, combine wine and next 5 ingredients in a jar with tight fitting lid. Shake well. Pour 2 tablespoons over fish, add garlic and turn to coat. Marinate 15 to 30 minutes, turning once. Reserve remaining vinaigrette for salad dressing. Coat grill rack with cooking spray and place on grill to heat 1 minute. Place tuna on grill 4 to 6 inches over hot coals. Cover with lid or tent with foil. Cook, turning once, just until tuna begins to flake easily when tested with a fork, about 7 minutes. Discard marinade.
Meanwhile, arrange salad greens on 4 plates. Place hot tuna on greens and add cherry tomatoes. Shake remaining vinaigrette and drizzle over salads.
