1. Toast coriander, fennel and cumin seeds in a small skillet over low heat 1 to 2 minutes, until seeds become fragrant and lightly colored. Cool completely. Pulse seeds in a spice or coffee grinder until coarsely ground. Combine garlic, salt and pepper in a small bowl; add ground spices. Rub mixture over all sides of meat. Transfer to a glass dish. Cover with plastic wrap and marinate in the refrigerator overnight.
2. Combine wine and oil in a small bowl; brush mixture on both sides of meat.
3. Heat and oil grill. Arrange meat on cooking grate. Cover and grill steak over medium heat about 20 minutes, turning once, until an instant-read meat thermometer registers 145 degrees F when inserted into the thickest portion for medium-rare. (Grill lamb, covered, 10 to 11 minutes per side until thermometer registers 145 degrees F when inserted into thickest portion for medium-rare.) Transfer meat to a cutting board. Let stand 10 minutes before slicing. Makes 8 servings.