Julienne leeks, courgette, celery and red pepper (cut into thin strips). Toss together with wine and olive oil and season lightly.
Preheat grill to medium-high and place on a fish rack to heat (or make sure grill is very clean). Rinse striped bass and fill cavity with julienne vegetables.
Place a few lemon slices inside each and 2 sprigs of thyme and 2 basil leaves.
Tie each fish at the center (or in 2 places if needed) to keep vegetables in. Brush outside of fish with any remaining oil/wine from the bowl and season lightly.
Place fish on heated grill rack and grill without moving for about 8 minutes. Turn fish over and cook, without moving for another 8 minutes, or until fish has cooked through.
Remove twine and serve.