Homemade Mayonnaise

In a double boiler or heatproof bowl over simmering water, constantly whisk the egg yolks, 1 tablespoon water and lemon juice until mixture reaches 160°, 30-40 seconds. While whisking, quickly place the bottom of the pan or the heatproof bowl in a bowl of ice water; continue whisking until cooled, 1-2 minutes., Transfer to a 2-cup glass measuring cup or other narrow container. Add salt and pepper. With an immersion blender, process mixture while gradually adding oil in a steady stream. Whisk in remaining 1 tablespoon water if desired. Cover and refrigerate for up to 7 days.