Clams on the Half Shell with Fresh Mayonnaise

Steps

1. 1Open the clams by inserting the edge of a butter knife right at the end where the most curved part of the shell is, next to the hinge, and levering it open. Do your best not to damage the inner meat with the knife. The meat is connected at the hinge and at the adductor muscle. Just scrape that off the shell of on both sides. Arrange on a serving platter and chill while preparing the mayonnaise.
2. 2Whisk together the egg yolk, salt, ground mustard, and sugar in a glass bowl. Combine the lemon juice and vinegar in another bowl. Whisk half of the lemon juice mixture into the yolk mixture. On a non-skid pad, whisk briskly, adding the oil a few drops at a time until the liquid seems to thicken and lighten a bit, which means you’ve got an emulsion on your hands. Once you reach that point, you can relax your arm a little and increase the oil flow to a constant, but thin stream. Once half of the oil is in, add the remaining lemon juice mixture.
3. 3Continue whisking until all of the oil is incorporated. Serve 1 teaspoon mayonnaise on top of chilled clams on the half shell.