1) In a large saute pan over medium-high heat, add the grapeseed oil. Season the fish with salt and pepper and add to the pan. Sear the fish for 3-4 minutes on each side. Add the thyme and juice of half a lemon and baste the fish with the sauce. Remove the halibut from the pan to a serving platter.
2) Add the olive oil to the pan and stir in the tomatoes, the garlic and the juice of half a lemon. Cook for 2 minutes and then add the parsley. Stir to combine and serve on top of the fish.