Heat grapeseed oil over medium heat in a saucepot. Saute the shallot and garlic until the shallots turn translucent, being careful not to burn the garlic. Stir in rosemary and thyme, add crushed tomatoes, season with salt and pepper, cover and let simmer for 15 minutes, then partially remove lid (leave it covered just enough to keep the spattering down) and reduce heat to medium-low, let thicken and reduce for another 15 minutes.
While the sauce is thickening, season the fish with salt and pepper. Arrange fish on a steaming rack and steam over a pan of boiling water until it flakes easily, about 6 to 7 minutes.
While the fish is steaming, remove the sauce from the heat and whisk in the cream. Strain the sauce into a bowl.
Spoon sauce into the center of serving plate, top with a fish fillet and fresh grape tomatoes. Sprinkle with parsley leaves.