1. Arrange the frozen king crab legs in a rimmed baking pan and squeeze the lemon juice over them.
2. Set the oven to heat to 350F, and when it’s ready, pour the hot water into the pan. Ensure it’s enough to cover the pan’s bottom. Then, wrap the tray tightly with foil so the steam is locked in.
3. Slide the pan into the oven and let the king crab legs cook for 10 minutes. Then, take the tray out and carefully remove the foil.
4. Crack open one of the crab legs to see if the center is hot. And if it is, then the recipe is ready. So transfer the crab legs to a plate, and serve with melted butter dip.

See this video if you need more tips.