Completely thaw lobster tail in the refrigerator.

In a large kettle, bring enough water to a boil to cover lobster tails; add 1 tbsp. salt for each quart of water, if desired.

Place thawed tails in boiling water. When water returns to a boil, reduce heat and simmer (do not boil), covered, for 5 min. for a 4 oz. tail. Add 1 min. for each additional ounce.

Remove from pot. Plunge into an ice bath to stop the cooking; drain.

Cut lobster tail lengthwise through center of hard top shell with kitchen shears; cut through meat with sharp knife without cutting through soft undershell.

Spread open; place on broiler pan. Brush with melted butter; sprinkle with salt.

Broil 4-6" from heat or bake in a preheated 350° oven until meat is firm (10-15 min., depending on size).

In a small saucepan over low heat, slowly melt desired amount of butter.

Remove from heat and let stand until the clear part can be spooned off into a serving dish (2-3 min.); discard milky solids. Serve warm.