1. Place eggs in a small saucepan. Cover with water to 1 inch above eggs; bring just to a rolling boil. Remove from heat; cover and let stand 15 minutes. Drain and rinse with cold running water until cool. Peel and slice eggs, and set aside.
2. Heat a large cast-iron grill pan over medium-high heat. Sprinkle fish with salt and 1/4 teaspoon pepper. Coat pan with cooking spray. Add fish to pan; cook 3 minutes on each side or until desired degree of doneness. Cut tuna steaks across the grain into thin slices.
3. Hollow out top and bottom halves of bread, leaving a 1/3-inch-thick shell; reserve torn bread for another use. Arrange 6 Quick Pickled Dilly Green Beans on each of 4 bottom bread halves. Arrange tuna evenly over green beans. Top with 2 tomato slices. Arrange the fennel over tomato. Divide olives among each of 4 top halves of bread; drizzle each top half of bread with 1 1/2 teaspoons oil. Divide arugula and sliced eggs evenly among top halves of bread, and sprinkle remaining black pepper evenly over eggs. Place the top halves of bread on bottom halves; cut each sandwich in half.