Place a large nonstick skillet coated with cooking spray over medium heat until hot. Add fennel seeds and garlic; sauté 3 minutes or until seeds are lightly toasted. Spoon mixture into a bowl. Add wine, olives, lemon juice, 1 teaspoon orange rind, and red pepper; stir well, and set aside.
Sprinkle black pepper and salt over tuna. Recoat skillet with cooking spray; place over medium-high heat until very hot. Add tuna; sauté 5 minutes on each side or until medium-rare or to desired degree of doneness. Remove tuna from skillet. Spoon couscous into each of 4 large shallow bowls; arrange tuna to the side. Set aside; keep warm.
Add wine mixture to skillet; cook 2 minutes or until sauce is slightly reduced. Pour sauce evenly over steaks. Garnish with orange rind, if desired.
Note: Substitute kalamata olives for Greek black olives, if desired.