Brill (or Griet for my Dutch followers) is one of my favourite fishes. Start with the veggies. Take about 12 cm of courgette. Slice and cut to make long matchsticks. Do the same with the leek.
Cut some cauliflower 3 mm thick. Lightly oil the fish fillets.
Stir-fry the leek/courgette mix in some oil till just soft enough. Panfry the cauliflower in butter. Not too soft or they'll fall apart. Panfry the fish, skin side down, till crisp. Turn off the heat and flip the fillets over to have the other side done in 2 mins while you start plating.
I was lucky to have some lobster fond in the freezer and stirred in a bit of creme fraiche.

Otherwise buy a box of frozen gamba's. Keep the brill till tomorrow and eat the gamba's today, just with some garlic, parsley and olive oil. Then use the heads and shells to make a stock with 2 halved onions, chopped carrots, celery sticks, halved tomatoes, a glass of white wine, a bay leaf and cold water. When done reduce the stock till thick and sirupy. Tastes as good as lobster. Well, almost.