BRILL BAKED ON GREEN AND WHITE VEGETABLES
The size of your brill will dictate the number of mouths it will feed. A medium to large brill will satisfy four to six diners, a smallish one two. It should be reasonably large so that it will withstand a cooking time long enough for the vegetables to get to know the fish juices.
You want a whole fish for this, so see what your fishmonger has; also take into account your cooking receptacles and the size of your oven.