Start by cutting up a small potato in 1 inch cubes and boil till soft. About 15 minutes.
Place the garlic cloves and salt in a small food processor and puree until smooth. You may want to add a couple of teaspoons of water to the garlic to help blend it and scrape down the sides two or three times to ensure that all of the garlic is finely processed.
Drain the potato, add to garlic and blend well for about 30 seconds.
Turn the machine back on and slowly drizzle in the oil with 1/4 cup. After the first 1/4 cup has been added, drizzle in half the lemon juice.
Continue alternating between 1/4 cup of the canola oil and and the remaining half of the lemon juice until you've added all of the oil and lemon juice. Alternating between the two is the key to proper emulsification which creates the light and fluffy garlic sauce. ( depending on the size of your potato, you may need more or less oil to get the thick consistency you are after).
You know the sauce is done when it has the consistency of thick whipped cream.