Halibut with zucchini

1/4 cup shallot , finely chopped 1/4 cup white wine vinegar 1/4 cup dry white wine 1/2 cup whipping cream 3 tablespoons vegetable oil 2 cups mushrooms ,[...]

2 halibut fillets (6 to 8 oz ea) 2 tablespoons butter 2 teaspoons chopped fresh parsley 1/2 red onion , finely sliced 1 zucchini , finely sliced 1 yellow[...]