Allow the steaks to stand at room temperature for 20 to 30 minutes before grilling. Lightly brush or spray the steaks with the oil and season with the celery seed, salt, and pepper. Grill over Direct High heat until cooked to desired doneness, 8 to 10 minutes for medium-rare, turning once [if flare-ups occur, move the steaks temporarily over Indirect High heat]. Remove the steaks from the grill and let rest for 3 to 5 minutes. Serve warm with the potato salad.