I found this dressing at seriouseats.com.
Ingredients:
2/3 cup ketchup 1/2 cup finely chopped onion 1/2 cup mayonnaise 1/3 cup red wine vinegar 1/3 cup granulated sugar 1 teaspoon Worcestershire sauce 1 teaspoon paprika 1/2 teaspoon garlic powder 1/2 teaspoon kosher salt 1/2 cup vegetable oil
Preparation:
Place ketchup, onion, mayonnaise, vinegar, sugar, Worcestershire sauce, paprika, garlic powder, and salt in the jar of a blender. Purée until onion is completely chopped. With the motor running, slowly pour in vegetable oil. Use immediately or transfer to an airtight container and store in refrigerator for up to 2 weeks.