1. Zest and juice lemon, reserving 1/4 teaspoon zest and 1 teaspoon juice.
2. Place flour in a shallow dish. Sprinkle fish evenly with salt and pepper; dredge fish in flour.
3. Melt butter in a large nonstick skillet over medium-high heat. Add fish; cook 2 to 3 minutes on each side or until fish flakes easily when tested with a fork or until desired degree of doneness. Remove fish from pan; keep warm.
4. Add garlic to pan; sauté 1 minute or until browned. Add wine; cook until liquid almost evaporates, scraping pan to loosen browned bits. Stir in tarragon and reserved lemon zest and juice. Pour garlic sauce over fish.