Preheat the oven to 400-degrees.
Drizzle ½ tablespoon of oil onto a rimmed baking sheet and then spread it evenly over the entire surface.
Place the fish fillet in the center of the baking sheet. Set aside.
Add all the prepared vegetables to a large bowl and add 1½ tablespoons of olive oil, 2 teaspoons coarse salt, and ½ teaspoon black pepper. Toss well to combine all the ingredients.
Pour the vegetables onto the baking sheet to surround the fish fillet entirely.
Season the fish with the remaining salt and pepper, and sprinkle evenly with the dill weed.
Top with fish evenly with the lemon slices and roast in the preheated oven for 25-30 minutes, or until the fish registers 145-degrees on an instant-read thermometer.
To serve, portion the fish into 6 pieces, and spoon the vegetables over, or next to, the fish.