Summarize:

Set a large pot on the stove and fill it 3/4 full with water. Put a lid on the pot and turn the burner to high. Heat the water until it begins to boil and you see steam escaping from under the lid. Then, wear oven mitts to carefully remove the lid and add salt to season the water. Plan on using about 1 tablespoon (17 g) of salt for every 4 cups (0.95 L) of water you add to the pot. Slowly lower 4 thawed lobster tails into the boiling water so they don't splash you. Keep the lid off of the pot and boil the tails until they turn bright red. If you stick a skewer into a tail, the meat should be tender once it's finished cooking. You'll need to boil the tails according to how much they weigh:  3 to 5 minutes for 3 to 6 ounce (85 to 170 g) tails 5 to 6 minutes for 6 to 7 ounce (170 to 198 g) tails 6 to 8 minutes for 8 to 10 ounce (226 to 283 g) tails 8 to 10 minutes for 10 to 16 ounce (283 to 453 g) tails 10 minutes for 16 to 20 ounce (453 to 566 g) tails While the tails are boiling, you can make a simple dipping sauce. Melt 8 tablespoons (112 g) of unsalted butter in a small pot on the stove. Then, turn off the burner and stir in:   4 1⁄2 teaspoons (22 ml) of lemon juice 1/4 cup (5 g) of chopped fresh parsley 1 teaspoon (5.5 g) of salt 2 teaspoons (4 g) of freshly ground black pepper Turn off the burner for the boiling pot of water and use tongs to take each tail out. Set them on a serving platter along with the pepper butter and your choice of sides. You could serve the tails with wedges of lemon, baked potatoes, or steamed broccoli, for instance. Refrigerate leftover lobster tails in an airtight container for up to 4 days.
Bring a large pot of water to a boil and add salt. Add 4 tails and boil them for 3 to 10 minutes. Heat the butter with lemon juice, parsley, salt, and pepper in a separate pot. Use tongs to remove the tails and serve them with the pepper butter.