Sprinkle the gelatin over the lemon juice in the container you're going to use for the dressing. Let the gelatin soften briefly, then whisk in the egg and microwave on high for about 35 seconds. You want to get the temp to 160 degrees to kill any salmonella in the egg. (I use an instant-read thermometer to make sure it has gotten hot enough, although in reality it's very rare to get sick from a raw egg. It's more for my own peace of mind than out of any real danger that I go through this procedure, but I'd need to heat the liquid anyway to dissolve the gelatin.) Once you've done this a few times you'll know how much time you need for your particular microwave. Use a stick blender if you have one to whir up the resulting mixture; if you've used a container that will accommodate the blender you'll end up messing up just that one item. Otherwise, you'll need to scrape the mixture into a regular blender and proceed from there.
Either way, after you've blended the egg/lemon juice/gelatin mixture blend in the vinegar and other ingredients minus the oil. Then slowly pour in the olive oil and blend until completely emulsified; you can tell this has happened when the color becomes lighter and the dressing looks creamy.
Chill thoroughly; the dressing will thicken somewhat after chilling.