Light about 3/4 of a chimney of charcoal, let it get hot, then dump it in your grill. If you are using a gas grill you can set it on medium-high
Melt your butter and squeeze in the juice of one lemon
Split of butterfly your lobster tails. If you are butterflying your tails insert the knife right in front of the tail and split down through the lobster leaving the tail intact.
Give the lobster meat a brush of butter and a light sprinkle of salt
Place the lobster meat side down on your grill until the meat is just starting to take on some color. This should take 2 minutes or so.
Cut the lemons in half and put them cut side down on the grill. When the start taking on some color remove them from the heat.
Flip the lobster tails, baste with more butter, and let them cook shell side down for about 2 more minutes. The lobster meat should be 135-140 degrees.
Remove the lobster tails from the heat and douse with the lemon butter. Serve with the grilled lemons.