1/2 c. plain low-fat yogurt
1/4 c. each low-cal mayonnaise, lemon juice
2 tsp. each chopped fresh parsley, grated Parmesan cheese, water
1 clove garlic, minced
1/4 tsp. anchovy paste (or 2 tsp. Worcestershire sauce)
Optional: a few fresh leaves of oregano or basil, minced

Combine ingredients and whisk smooth. Store in refrigerator, covered. Makes about 1 1/4 cups - less than 20 calories per tablespoon.