Preheat the oven to 350 F. Place the fish on a plate and pat it dry with paper towel to ensure even cooking. Season the fish on both sides with garlic powder and paprika.
Place the prepared green beans and sliced tomato halves in a bowl with the Italian seasoning, salt and pepper. Spray with a little cooking spray then toss to combine.
Place the veggies in a 13-inch by 9-inch casserole dish in an even layer (or a sheet pan). Place the halibut on top of the veggies.
In a small bowl, prepare the lemon oil sauce. Mix then drizzle over the fish.
Bake 15-20 minutes until the fish is opaque and flakes easily with a fork and veggies are al dente. Serve immediately.
Notes
The recommended internal temperature for fish is 145°F. It should be opaque and easily flake apart without being dry.
If you use frozen fish, thaw it in the refrigerator for 24 hours and then pat it dry to ensure even cooking.
Reheat leftovers in the oven at 275°F until they are warmed through.