How to Cook Lobster Tails - Bring a pot of water to a boil and add a pinch of salt. Add the lobster tails. Simmer then until they are done. Count on them taking between 4 and 10 minutes depending on size. When the shell changes color and the meat turns from glossy to opaque, the tails are ready. Let them cool for 5 minutes, then use sharp scissors to cut down the shell, so you can pull the meat out. Put the meat back in the shell and serve with the melted butter and lemon wedges.