Put the egg in a food processor or electric blender and process for 30 seconds. Add the salt, pepper, dry mustard and lemon juice. Pulse two or three times to blend. While the motor is running, gradually add the oil through the feed tube. The mixture will thicken. Adjust seasoning to taste if necessary.
Store in an airtight container in the refrigerator for up to 24 hours. *** Because this is made with raw eggs, be sure to use fresh eggs (check the expiration date on the carton), and don't serve this mayonnaise to small children, the elderly or those who have health problems.
The mixture can be used as a sandwich spread, a salad dressing, or a dipping sauce for boiled seafood. Makes 1 cup