In a blender or food processor, whirl egg, lemon juice, garlic to taste, and 1/4 teaspoon salt until well blended.
With machine running, gradually add olive oil in a thin, steady stream until all is incorporated.
Add more salt to taste.
Quick Aioli: Omit the egg and oil, and use 1 cup purchased mayonnaise instead. Whirl mayonnaise with lemon juice, garlic, and salt until smooth. Makes about 1 cup.