Tartare sauce

Place the egg yolks and lemon juice in the bowl of a food processor and process for 30 seconds or until well combined. With the motor running, gradually

Add the oil in a thin steady stream until mixture is thick and pale. Transfer mayonnaise to a medium bowl

Add sour cream, gherkin, onion, capers, parsley and extra lemon juice to mayonnaise, and stir to combine. Taste and season with salt and pepper. Transfer to a serving bowl, cover with plastic wrap and store in the fridge until required