Marinate the fish with salt, 1 teaspoon crushed peppercorns and ½ tablespoon olive oil.
Heat 1 tablespoon butter in a non-stick pan. Add shallots and sauté till translucent.
Add fish stock, stir to mix and cook.
Chop 3 tablespoons tarragon and add in the pan alongwith cream and mix well.
Add ¼ cup butter gradually and whisk well to form a homogenous mixture and cook for 10-15 seconds.
Strain the sauce and add parsley and remaining chopped tarragon.
Heat ½ tablespoon butter and remaining olive oil in a non-stick grill pan. Place marinated fish pieces on it and sear for 15-20 seconds on each side.
Add asparagus pieces, salt and remaining crushed peppercorns and cook further.
Heat the prepared sauce.
Place asparagus on a serving plate and put the cooked fish on top. Pour the heated sauce over it and serve immediately.