Lightly season fish fillets with salt and pepper. In a large skillet over medium heat, heat oil until hot.
Add fish, skin side down; cook until golden, about 4 minutes. Turn and cook until opaque, 3 to 4 minutes longer. Remove to dinner plates; cover with foil to keep warm.
Add onion to drippings in pan; cook and stir until lightly browned. Stir in wine, vinegar, honey and 1 tablespoon water; cook and stir over medium heat until reduced to about ¼ cup. Stir in butter; heat until melted. Stir in grapes and tarragon; return just to a boil and remove from heat.
Spoon sauce over fish. If desired, serve with puree of sweet peas.
Recipe by Webicurean at http://blog.webicurean.com/2008/06/05/pan-seared-fish-fillets-with-chilean-grapes/