Fill a medium sauce pan with water. Bring the water to a boil over medium-high heat.
Place the eggs into the boiling water, and boil for six minutes for soft-boiled, or eight minutes hard-boiled.
Prepare the Vinaigrette
In a small jar with a tight-fitting lid, combine the grated garlic, salt, pepper, sugar, lemon juice, and the oil.
Screw the lid onto the jar tightly, and shake vigorously to create an emulsion.
Peel the Eggs
When the eggs have finished boiling, fill a mixing bowl with ice water, and transfer the eggs to the ice water.
Knock the egg's shell against the hard countertop to break the shell. Peel away the eggshell and discard.
Set the eggs aside until you're ready to assemble the salad.
Assemble the Salad
Just before you assemble the salad, slice the avocado. Set it to the side so you can scoop the flesh directly onto the arugula salad later.
Put the arugula into a large mixing bowl.
Give the vinaigrette another vigorous shake just in case it needs to be emulsified again.
Pour half of of the dressing over the greens. Save the remainder for pouring on later, if you wish, or for another day.
Toss to coat the arugula with the vinaigrette.
Slice the eggs in half and top the salad with them, then add the red onion slices, and, finally the avocado.
Add more dressing, or salt and pepper, if you wish.
This salad is best enjoyed right away.
Notes
To prepare this salad in advance (for work or school lunches):
Pre-cook the eggs to your preference. Do not peel them, though. When you're ready to assemble your salad, peel and cut the eggs.
Prepare your dressing as instructed, leaving it in the mason jar for easy transport. Shake again, just prior to dressing your salad.
Cut the avocado in half and slice like you normally would (cut around the seed). Instead of scooping out the seed and the flesh, reassemble the avocado (put the two halves together again). Wrap the avocado in plastic wrap and place in an air-tight container, or plastic food storage bag. This will prevent the avocado flesh from oxidizing (turning brown).