In a large bowl combine egg, bread crumbs, oregano, garlic, salt, pepper, and 1 tablespoon water. Add lamb; mix well. Form into eight 4-inch-long logs.
Grill lamb on the rack of an uncovered grill directly over medium coals for 14 to 18 minutes or until lamb is no longer pink, turning once. (Or, place in shallow baking pan. Bake in a 400 degree F oven for 12 to 14 minutes.)
Meanwhile, spread the cracker bread or tortillas with hummus. Sprinkle with spinach or lettuce, feta cheese, and olives. If using cracker bread, place 4 lamb pieces, end to end, near an edge of each round. Roll up, beginning with edge closest to lamb. Slice each roll-up diagonally in fourths. (If using tortillas, place 2 lamb pieces, end to end, on each tortilla. Roll up. Slice each roll-up diagonally in half.) Makes 4 servings.