Blend on blend speed until well mixed:

1 lg. egg
2 tbsp. vinegar or lemon juice
1 tbsp. Worcestershire sauce
1 rounded tsp. dry mustard
2-3 cloves garlic
1 sm. onion (opt.)
1/2 tsp. salt
1/4 c. oil or to cover blades

Gradually add 3/4 cup or more oil in a slow steady stream. Mixture will thicken like mayonnaise. By hand, stir in 2 tablespoons Parmesan cheese. Yields about 1 1/4 cups. Keeps well in refrigerator.