1/3 c. fresh lime juice
1/2 c. (1 stick) chilled butter, cut into 8 pieces
4 tbsp. chopped fresh cilantro
3 tbsp. light olive oil

Boil lime juice in heavy small saucepan over medium-high heat until reduced to 2 1/2 tablespoons, about 2 minutes. Remove from heat and whisk in 2 butter pieces, one at a time. Set pan over low heat and whisk in remaining butter pieces, 1 piece at a time. (If sauce breaks down, remove from heat and whisk in 2 butter pieces.) Remove from heat, then whisk in cilantro mixed with olive oil.

Serve over shrimp, squid or other fish.