Preheat oven to 375 degrees F.
Take two large pieces of aluminum foil and place one halibut fillet in the middle of each piece of foil. Curve the ends of the foil, creating a bowl, so you can put liquid in without it falling out.
Put 3-4 Tbs of lemon juice on top of each fillet. Top each fillet with heavy pinches of sea salt and black pepper.
Then top each fillet with 1.5 Tbs of greek yogurt. Add a branch of fresh rosemary to each fillet, and a slice of lemon as well.
Push foil around the top of the fillets until aluminum packets are closed.
Cook the fish for 20 minutes. ( Cook time will be more or less depending on how thick your piece of halibut is )
Note: Don’t throw away the sauce! Use the lemon greek yogurt rosemary sauce on top of rice, potatoes or veggies.