Plaki typically refers to a Greek baked fish dish with vegetables. My Nona (grandmother) made a dish she referred to as Plaki. The recipe, long forgotten, is a bit of a mystery and all I remember is that is contained green grapes and mild white fish. I thought I would give it a try for Passover, since we eat a lot of fish over the holiday.
I combined vegetables that appear in Turkish and Greek cuisine frequently and would compliment each other and the halibut. The results were beautiful and tasty. Flaky white fish with the intriguing flavor of fennel, sweet from grapes and acid of tomatoes with some gelled lemon and mildly celery flavored juice makes a tasty fish course. 
1.5 pounds of fresh halibut filet
2 tablespoons olive oil
2 tablespoons lemon juice
1 celery rib, finely diced
¼ small Spanish onion, finely diced
1/3 cup fennel, finely diced
1 small carrot, finely diced
¼ red bell pepper, diced
10-14 green grapes cut in half
10 grape tomatoes cut in half
1/3 cup chopped parsley
Wash the halibut filet and pat it dry. Pour the oil in a baking dish that fits the size of the fish filet. Place the fish filet in the dish, pour the lemon juice on top, and season the fish with salt and fresh cracked pepper.
Mix all the chopped vegetables in a small dish. Spread the vegetables on top of the fish, place the grapes on top of the vegetables, and sprinkle the parsley on top of all. Bake the fish in a 350º oven for about 30 minutes. If the vegetables seem a little underdone, cover the baking dish with aluminum foil to prevent further browning and bake for another 10 minutes.   
Plaki keeps refrigerated for up to 3 days.