Method:
Heat butter in a large, deep skillet over medium-low heat. Add shallot and cook until softened, 3 to 4 minutes. Add white wine, increase heat to medium and cook until liquid is reduced by half, about 4 minutes. Add fish stock, tomatoes and tarragon. Bring sauce to a boil, reduce heat to a simmer and cook 10 minutes. Season fish with salt and pepper. Add fish to skillet, spooning tomatoes on top. Cover and simmer until fish can be flaked and is fully opaque, about 10 to 15 minutes. With a slotted spatula, transfer fish pieces to a platter.
Add orange juice to skillet. Simmer sauce, uncovered, over medium heat for 10 minutes to reduce slightly. Taste sauce and adjust seasoning. Spoon over fish and garnish with fresh tarragon or parsley.