Spread the lobster out on the cutting board, flatten the tail out if it is curled. Press the point of your chefs knife against the head of the lobster, about 1/2 inch from the eyes, right in the middle. Press down firmly until you hit the cutting board. Work the knife cutting to the back of the lobster, at the top of the tail. Firmly press the knife down, splitting the tail in half. Turn the knife around, placing back into the first place you cut, press down firmly to split the head in half.